Tractor AC compressor

Going to start with this short then expand as necessary.

I only have 150# across my compressor (15-165#) when testing per the manual at 1500 rpms. Manual says I should have more like 200 (25-225)on a 90* day . Dryer was replaced, vac pulled 26" 30 min, new 134a fill to at least 95% max. Cab hot, condenser coil right at ambient.

I think my expansion valve is opening because once turning off the system, it takes 2 minutes for the system pressures to stabilize to 110#. If it were closed would it do that so fast? What would be the path? Do compressors in serviceable condition block freon when off? I would expect so since they build pressure through the same ports/mechanisms.

Replies appreciated.

What is the static pressure tomorrow morning. Pressure should be near or slightly above the ambient temperature, i.e. 80 degrees and 80 psi.
Sounds you are a little low on R134.

Hello Texasmark1,

Gauge pressures seem to indicate low refrigerant charge. What is the vent outlet thermometer reading? 26" of vacuum and 1/2 hour, does not sound enough also.

Try adding some refrigerant and see if the vent temp goes down.As long as the temp keeps going down, you keep adding refrigerant. Keep an eye on the low side pressure. You are looking for a minimum of 20# max of 50#. Your low side going into the compressor should be sweating, if not that indicates a low charge too.


Guido.

The register output is 95F as is the cab as is the condenser coil.

I just bought the pump and tested it closed, not connected to a system. It pulled down to 30 instantly. The tractor manual specifies the total charge. If I drain the partially filled can connected currently I will be over the manual's capacity number. The system hasn't been open but for a minute or two and I have no cooling so there is no frost. I could still have a leak and that would be the reason for the 26 and not 30 or there was still some freon in the system boiling off.

I don't understand why the system isn't starting to respond to the 95% fill as it is. It's been a long time since I did much AC work and at 78 things aren't as sharp as they once were. I had a correspondence course in Heating, Ref., and AC, years ago and haven't done much AC work since...been lucky I guess. I do my own when I have a problem. Recollecting in autos over the years, when the charge would get low, the AC would put out cool, not cold air. This one currently puts out nothing.

I had a leak for quite awhile and finally added a popular AC leak stopper per the can's directions as I couldn't find the leak. The system has been acting funny ever since. So I replaced the dryer and am trying to understand where the system is in equilibrium at this point. I didn't want to add this info initially as I wanted help understanding the expansion valve operation to help in understanding if I clogged it when using the leak stopper. As it stands right now, I don't think I did.

The other part of it is I have been down the over charging road with this system before and I may have damaged the compressor in doing so. I would add freon and gauges would barely respond and all of a sudden bang, big pressure spikes on the high side. Bleed off some freon and they'd stop. Was looking for user info. on what to expect from the compressor in terms of acceptable pressure drop which I assume is linear with amount of freon fill up to 200# at full charge.

Adding insult to injury, I can't find an expansion component, be it a cap tube or expansion valve, as a separate item in the AC system parts list...may come as part of a replacement evaporator core.....ugh! A new compressor is 400 bucks and if I need it I need it but don't want to just throw components at this problem just to find out, oh it wasn't that.

If I don't get some more ideas on the two components tonight or tomorrow morning, I guess I'll add some more freon tomorrow and see what happens. I still feel that cooling should be a linear thing (until somebody tells me, or I read that it isn't) and having installed 95% of the service manual's listed max fill, sitting on 3 ½ cans and full is 3.89. I should be getting some kind of cooling and nada.

Thanks. Still listening....

What is the low side pressure? Was the system properly vacuumed to remove all air from the system prior to charging?

Your AC system high pressure would appear low to me. On a 90+ I get my AC high pressure in the 250 psi range. How many oz's of refrigerant have you installed in your tractor's AC system?

3.5 12 oz. cans. Manual says capacity is 3.89.

I said I vacuumed for 30 minutes. That was the first period. When finished I shut off the gauges and the low side moved up from about 24 to 12 in just a minute or two....I said got more to go, so I opened the valve again and pumped for another period...did not track time. Checked again and was at 26 and closing the valve the needle moved down to around 20 and stopped. I figured that was good enough. Pump is a brand new $90 2.5 cfm HF pump....a real beauty.

7 AM: Ta 75F, low 83, high 80#.

If you want to verify a good compressor, block the condenser with a piece of cardboard or plywood, pressure should rise above what you're showing now.

Now that we are getting some responses here and some thoughts: The leak sealer product can only held a few oz of sealer and the rest propellant....can size about the same size as the little 134a 2 oz oil additive can for a system that has a 45+ oz freon fill.

Upon removing the dryer, I was curious as to the makeup of a dryer and the contents; shape was 2 1/2 D x 8" L. Contents were an open cylinder with a pair of horizontal discs, with one layer of 1/16"balls (assumed to be the desiccant.....not nearly as much as I was expecting) sandwiched between 2 perforated plates situated about midway down the cylinder. Coming up from the bottom of the cylinder was a tube in the center of the discs extending to the top. I'd assume the inlet was into the cylinder and the outlet was via the tube...lost track in the disassy as to which was which. In the bottom (cylinder vertically mounted) was some ref. oil and probably a tablespoon full of tiny crystal (reflective) chip looking things, not some kind of goo as I was expecting.

I am under the opinion that I have a clog preventing the movement of freon through the system thus the reason for absolutely no cooling, and no temperature rise of the condenser coil. Being a closed system, I "think" i can understand that if you are pulling against a blockage, you have no product to compress to the point of over pressuring the high side against blockage. I have also seen in you tube videos that the passages on the condenser were partially blocked and passing the non contact infrared thermometer across the condenser coil gave different temperature readings giving the location of the blockage. The narrator went further to explain that the passages are small and to attempt to clean one is a waste of time and one should just replace it. I really think that those little granules weren't sufficient in quantity to block the evaporator or the condenser.

I keep thinking that the expansion valve is the culprit, but if so, how can I shut off the engine and the pressures are equal in 2 minutes, exponential decay?

More ideas? Thanks

Lit it off this AM and started adding the rest of the current can of freon. As it was completing, making for the exact amount the manual said was full, the high pressure shot up from 180 to 300 ish and the suction pressure dropped from the previous low reading...down to around 10. I have a troubleshooting chart that says I have a clog preceding the evaporator....aka expansion valve clogged I'd bet. So, today it's rig up 2 ropes from the barn rafters and lift the top off the cab to access the evaporator and all and get at the expansion valve. Will stay tuned.

(quoted from post at 07:33:12 07/23/20) Now that we are getting some responses here and some thoughts: The leak sealer product can only held a few oz of sealer and the rest propellant....can size about the same size as the little 134a 2 oz oil additive can for a system that has a 45+ oz freon fill.

Upon removing the dryer, I was curious as to the makeup of a dryer and the contents; shape was 2 1/2 D x 8" L. Contents were an open cylinder with a pair of horizontal discs, with one layer of 1/16"balls (assumed to be the desiccant.....not nearly as much as I was expecting) sandwiched between 2 perforated plates situated about midway down the cylinder. Coming up from the bottom of the cylinder was a tube in the center of the discs extending to the top. I'd assume the inlet was into the cylinder and the outlet was via the tube...lost track in the disassy as to which was which. In the bottom (cylinder vertically mounted) was some ref. oil and probably a tablespoon full of tiny crystal (reflective) chip looking things, not some kind of goo as I was expecting.

I am under the opinion that I have a clog preventing the movement of freon through the system thus the reason for absolutely no cooling, and no temperature rise of the condenser coil. Being a closed system, I "think" i can understand that if you are pulling against a blockage, you have no product to compress to the point of over pressuring the high side against blockage. I have also seen in you tube videos that the passages on the condenser were partially blocked and passing the non contact infrared thermometer across the condenser coil gave different temperature readings giving the location of the blockage. The narrator went further to explain that the passages are small and to attempt to clean one is a waste of time and one should just replace it. I really think that those little granules weren't sufficient in quantity to block the evaporator or the condenser.

I keep thinking that the expansion valve is the culprit, but if so, how can I shut off the engine and the pressures are equal in 2 minutes, exponential decay?

More ideas? Thanks

Click to expand...

3.89 charge is a little shy of four lbs freon. three cans @ 12 oz is a little over 2 pounds of freon, vacuum until the gauge does not rise or fix the leak. Stop leak wont help.Use pag oil with "ice" for better cooling. Make sure the belt for the radiator fan is not slipping, air flow across the condenser is very important, the expansion valve is likely inside the evap case, feel the low side plumbing as close to the evap or at the pump while charging, it should get cold as the system fills. If there is no cooling or the high side goes crazy spikeing with more than 275 psi, either there is not enough air across the condenser or the expansion valve is malfunctioning. Feeling the low side for cold will inform you of function,the pressures at the gauges are not the whole story, rather an indication of system efficiency. How long the system hisses after shut down is not info to guide you. Knowing there is air flow across the condenser, knowing the full charge, feeling the low side, high and low side pressure @ FULL charge are usable info. A restriction such as a stopped up exp valve would yield very high high side psi and very low or negative psi on low side.

You say that the manual says 3.89 is the capacity. 3.89 what? Ounces? Pounds? Cans?

OK, so I will assume it means pounds. 16 ounces in a pound times 3.89 is 62.24 ounces. Divide that by 12 ounces in a can and you get roughly 5.18 cans for a full charge.

Your statement that the high side pressure jumped up to 300 would indicate that your compressor is working OK. Might not be up to 100% efficiency, but it should be working enough to get cooling.

Usually, when the low side pressure is too high, it points to the expansion valve. But, if your numbers look like it should be cooling, it might indicate other problems. Too much moisture or air in the system are deadly to an A/C system. Air is simply a non-condensable gas at A/C system temperature and pressures, and will not allow any cooling - even if the pressures look OK. Another possibility is oil. If there is too much oil in the system, cooling performance will be poor.

Vacuum - on a standard day - (70 degrees at 29.92 atmospheric pressure) your vacuum pump should pull it down to an indicated 30 inches of vacuum. The system should hold that vacuum for at least 20 minutes or you have a leak big enough to cause problems. For leak checking, I like to use a combination of a leak detector and dye with black light. (I know, a lot of guys do not like dye checking. Heard it all). Look at connections, fittings, and the compressor shaft. If no leaks are found, REPLACE THE HOSES!!! Been there, done that! 134 refrigerant has a tendency to migrate through hoses as if they were porous. Those leaks are nearly impossible to find.

For as simple as a refrigeration system is, they can really give you fits trying to get them to work as they are supposed to. Good luck.

Not telling you to do this but I have flushed out condensers and evaporators with gasoline then blow air threw them to dry. This is very dangerous while blowing the air because of the vapor. Only outside no sparks.last tractor I worked on I replaced the expansion valve, no help. Took the evaporator out squirted gas through a few times then blew out. Put it back together and is still cooling good. Been about 5 years now.

Of the comments, you are closest to my current situation.

Accessed the expansion valve and removed it...has a capillary line and an equalization line. I can see why the evaporator mfgr included it in the evaporator
assembly package with one tractor part number rather than separating it out at the component level.

Disassembling the input (hollow) hex screw and removing the spring, I found it gummed up whereby it be surely could have been hampered in being
compressed by the capillary line (sensor) diaphragm when told to open, or not reseating the ball valve when required and the space around the ball valve
where freon was to move when unseated was pretty dirty also. Acetone and a wire brush cleaned the spring and cotton swabs with acetone cleaned the
cavity. I checked online and couldn't find a BF153GD. I had the tractor running when I found it and the TXV was completely frosted up. Recalling that is a
symptom of blockage, not allowing enough volume of freon past the valve to keep the input warm and the expansion effect within the evaporator......check
me on that if you would.

Agree that the compressor can put out a 300# differential...belt is tight, condenser and evaporator coils are clean inside and outside. Blew 100+
compressed air through the whole system and got what I would call adequate air flow.

I did find a bit of oil in the high pressure line from the compressor up to the TXV but not more than a couple of table spoons full.....doubt that would be
considered oil loading the TXV.

Since I can't find a BF153GD expansion valve on the www, I am forced to ensure my current one is as clean as possible and put it back in. Then on the
vacuum, I will stay at it...especially since I had most every connection open today, and get all the moisture I can out of it.

I checked my numbers on the capacity of the system and it verified the numbers for me as once I had put in the full amount and still had some left in the
can, not but a few minutes and the high pressure shot up into the 300# range while the low side was 10 or somewhere low.

Do appreciate you guys time and thoughts. We'll see how this saga plays out.

(quoted from post at 11:45:21 07/23/20) Of the comments, you are closest to my current situation.

Accessed the expansion valve and removed it...has a capillary line and an equalization line. I can see why the evaporator mfgr included it in the evaporator
assembly package with one tractor part number rather than separating it out at the component level.

Disassembling the input (hollow) hex screw and removing the spring, I found it gummed up whereby it be surely could have been hampered in being
compressed by the capillary line (sensor) diaphragm when told to open, or not reseating the ball valve when required and the space around the ball valve
where freon was to move when unseated was pretty dirty also. Acetone and a wire brush cleaned the spring and cotton swabs with acetone cleaned the
cavity. I checked online and couldn't find a BF153GD. I had the tractor running when I found it and the TXV was completely frosted up. Recalling that is a
symptom of blockage, not allowing enough volume of freon past the valve to keep the input warm and the expansion effect within the evaporator......check
me on that if you would.

Agree that the compressor can put out a 300# differential...belt is tight, condenser and evaporator coils are clean inside and outside. Blew 100+
compressed air through the whole system and got what I would call adequate air flow.

I did find a bit of oil in the high pressure line from the compressor up to the TXV but not more than a couple of table spoons full.....doubt that would be
considered oil loading the TXV.

Since I can't find a BF153GD expansion valve on the www, I am forced to ensure my current one is as clean as possible and put it back in. Then on the
vacuum, I will stay at it...especially since I had most every connection open today, and get all the moisture I can out of it.

I checked my numbers on the capacity of the system and it verified the numbers for me as once I had put in the full amount and still had some left in the
can, not but a few minutes and the high pressure shot up into the 300# range while the low side was 10 or somewhere low.

Do appreciate you guys time and thoughts. We'll see how this saga plays out.

Click to expand...

What tractor are you playing with (make/model)?

When you unscrewed and removed the calibration screw from the TXV did you carefully count turns, then put it back as close as possible to where it was?

Hello Texaxsmark1,

Just a couple of things. One is that the vacuum dropping was an indication of moisture in the system. Ones a good vacuum is done, the reading with the pump on should not change. It then should not change for at least 1/2 hour, indicating no leak.

Pressure on the other end pushes outwards, so at times with no vacuum leaks, it may still have a leak.
Testing the pump without load? Not a good test. As the vacuum pump runs and evaporates system moisture, the vacuum reading increases. Pull a vacuum for an hour or two, again stopping the pump to check for leaks and the gauge reading not dropping,

Guido.

Both high and low sides are low. You're low on freon. What are you working on? Was this originally r134a or is this a retrofit?

(quoted from post at 23:53:04 07/23/20) Both high and low sides are low. You're low on freon. What are you working on? Was this originally r134a or is this a retrofit?

Click to expand...

eah, I'm still hung up on 3.89 cans vs 3.89 pounds, myself?

(quoted from post at 20:53:04 07/23/20) Both high and low sides are low. You're low on freon. What are you working on? Was this originally r134a or is this a retrofit?

Click to expand...

I'm with you, JDIH, don't understand WHY the O.P. didn't share those important details in his first post.

Heck, he won't even tell me if he counted turns and put the expansion valve "superheat" adjustment back near where it was before he unscrewed it. (Oh, wait, "superheat", WHAT'S that?)

But, no worries, the "GURUS" have it all diagnosed even without that basic information being revealed, LOL!

Yes YES Yes : )

If I am reading this is a retrofit from R12 (3.890 LB 62 oz) to 134A the correct charge should be 80% of R12 = 49.68 oz. Just a little more than 3 lbs (3.168)....

I have yet to see he has an expansion valve issue... At first YES till the other info was posted... The expansion valve could be partially clogged @ 10 but it may be normal @ 10... When you get that low on the low side with no cooling and the high side in rage I want to make sure evaporator is free and clear for good air flow across it (dirt + moister turns into mud)...

You can feel your way back on the liquid line to find if its obstructed before the expansion valve.....

(quoted from post at 21:37:25 07/23/20) yeah, I'm still hung up on 3.89 cans vs 3.89 pounds, myself?

Click to expand...

I've never seen a manual specify refrigerant in terms of "cans," only in "pounds."

My assumption until about 5 minutes ago was 1 can = 1 pound. I really could swear that the cans used to say "net weight 16 fl oz." Looking at my supply, they're 12oz cans.

Maybe the OP has fallen for the same assumption?

Problem is he is counting 12oz cans as
pounds even after it was pointed out he
is 4oz shy of a pound on every can.
Didn't factor in the 80 percent
conversion amount either. Yet to see
where a full vacuum was pulled. The 300
lb pressure right after dumping in the
refrigerant is meaningless.

This isn't going to get fixed until good
clean airflow across both coils is
assured. O rings replaced on every
broken connection replaced and a good
vacuum pulled. Then the proper amount of
refrigerant ( in ounces ) added. Only
then can you troubleshoot the system.
JMO

(quoted from post at 08:40:38 07/24/20) Problem is he is counting 12oz cans as
pounds even after it was pointed out he
is 4oz shy of a pound on every can.
Didn't factor in the 80 percent
conversion amount either. Yet to see
where a full vacuum was pulled. The 300
lb pressure right after dumping in the
refrigerant is meaningless.

This isn't going to get fixed until good
clean airflow across both coils is
assured. O rings replaced on every
broken connection replaced and a good
vacuum pulled. Then the proper amount of
refrigerant ( in ounces ) added. Only
then can you troubleshoot the system.
JMO

Click to expand...

I am with you on replacing orings, air flow, vacuum, and charge. That said the total charge amount may not be guaranteed by the 80% calculation. Witness the 1989 k1500 chev at my the shop this moment. I have just finished rebuilding both drive axles and the a/c. The a/c was retrofit with new comp and accum a year or so ago by who knows, not me. The truck came in with leaking condenser. I installed a new condenser, new evaporator,orifice tube,o-rings,pag oil(w/ice) replaced the recirc actuator, cleaned the hvac housing and air distribution duct, installed new foam seals for air distribution. While pulling vacuum I checked published charge, "2.8 lbs"(r12). When charging, the low side reached "hard cold" @1.75 lbs.charge amount. I added an additional 2oz. and test drove the truck,,,coldest retrofit job I've ever done. The high and low side numbers were correct relative to ambient and RPM/airflow. The fan clutch moved air correctly. The cab was more air tight than most old trucks, the ambient temp was 100+ and it was frigid inside. I wish my junk made such cold air.
For me the 80% calc is not scripture, super heat and feel have worked consistantly for me since retrofit began maybe 20 years ago.

I did the cross reference since i was adding cans.

As it turned out, the Branson dealer parts guy had the gumption to dig around and find out that the expansion valve could be supplied with out having to
have the whole evaporator. That and the thought to be leaking HP hose from the compressor to the condenser are on order. Hear you on the tweaking the
SH setting.

I wasn't counting 12 oz cans as a #.

"I'm with you, JDIH, don't understand WHY the O.P. didn't share those important details in his first post."

Because I wanted 2 simple questions answered, not a total cooling system dissertation which would have come had I supplied any details initially.

I'll have to have another look at that. Good questions.

134a......

The instructions with the pump said 30 minutes. Hear you on the suck and blow are different stresses on the system for testing. It was sucking water alright. Foggy mist coming from the exhaust of the pump.

2007 Branson 6530 I bought new when I downsized and sold off my JDs. Been a real nice companion over the years.

For you folks who can't get out to the movies this evening, due to the pandemic distraction, get out the beer and popcorn and tune into this. There is something to be learned however.....gotta dig to find it.