Air conditioning experts

My IH 1086 had a new Sanden compressor, hoses, expansion valve, receiver dryer along with the high flow fan installed a couple years ago. It is on 134, the only thing original is the evaporator and condensor. Lately the system will kick out and the red light will come on when the engine is run fast. Putzing around at low engine speeds the air works fine.

I am no air conditioning expert, I know just enough to be dangerous so this is why I am on here asking you guys for advice. Last time it acted like this was right after the conversion was done, the system wasn't charged up quite enough. I could throw another can in it now but is there something else that can cause it to do this? My son has the gauges but he is busy right now and I don't feel comfortable using his gauges. If the system is low obviously there is a leak somewhere but I want to just get by with it for awhile. Thanks

(quoted from post at 12:59:26 06/02/21) My IH 1086 had a new Sanden compressor, hoses, expansion valve, receiver dryer along with the high flow fan installed a couple years ago. It is on 134, the only thing original is the evaporator and condensor. Lately the system will kick out and the red light will come on when the engine is run fast. Putzing around at low engine speeds the air works fine.

I am no air conditioning expert, I know just enough to be dangerous so this is why I am on here asking you guys for advice. Last time it acted like this was right after the conversion was done, the system wasn't charged up quite enough. I could throw another can in it now but is there something else that can cause it to do this? My son has the gauges but he is busy right now and I don't feel comfortable using his gauges. If the system is low obviously there is a leak somewhere but I want to just get by with it for awhile. Thanks

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know A/C pretty well, but not specifically the 1086. What is red light monitoring? Without knowing pressures, I don't see much diagnosis being possible.

R134 is very picky about the charge level. A little too much and the cooling level drops dramatically, it's not forgiving like R12 used to be.

The red light coming on could be high head pressure. High head pressure is caused by over charge or lack of air flow through the condenser. Could the condenser be clogged with grass, or the condenser fan not working?

On IH's of that era, including trucks, there is a low pressure switch near the evaporator that latches a relay to stop voltage to
the A/C clutch. You have to cycle the key to unlatch this relay. The low side/suction pressure drops as you raise rpm, so if the
switch senses too low of pressure it cuts out. You are most likely low on refrigerant. I have seen trucks where every thing was
fine and had to unplug the switch so the A/C would stay running, even with a new switch. But it should be checked with gauges
first, and verified for a leak. Mark.

The red light is low refrigerant warning. Mark.

Based on what you wrote and ASSUMING it has a low pressure cutout switch in the low side I'll venture to guess the low side pressure is dropping low enough to trip the low pressure switch causing the warning light relay to lock out.

Could be slightly low on charge, or the expansion valve could be partially clogged or the superheat not set correctly for R-134.

Most auto supply houses have loaner gauge sets.

A co worker shared with me that he believed that some AC systems will leak down during the winters coldest weather and not during the summer. It's difficult to find a leak when it isn't leaking and of course during the winter, who is looking for a leak then.

No idea about an IH but Ford used an
adjustable low pressure switch that
sometimes gets off. The adjusting screw
is in the plug. Course you need the
guages to set it.

fixerupper,

Sounds more like lack of condenser air flow then low refrigerant. After the unit has been running on low
speed for at least 10 minutes, check the temperature of the low side hose or pipe. You can convert the
temp to pressure. It usually is at this point 2 degrees warmer then the refrigerant. Check the temperature
chart to see what the pressure is.

On a fully charged system the low side going back the the compressor will have condensation up to the
compressor,


Guido.

Does the dryer have the little round window on the top so you can check for bubbles?

Beagle

Low charge would e my first guess, but it would just be a guess without looking at gauges. Most systems are set up
to run between 25 and 45 psi on the low side. Compressor would cycle off at 25 and restart at 45. Most systems that
are designed for R134a also have a high pressure cutout switch located on the high side line. Pressures can get a
bit out of hand on systems running R134a.

There is also the possibility that your compressor is running too fast. If your system is set up for mostly low
engine speed operation, when you raise up the engine speed, it could be running too fast resulting in lower
pressures on the low side and higher pressures on the high side. Again, without looking at gauge readings, this is
also just a guess.

Thank you guys for the suggestions. The receiver dryer does have a window. Removing four easy screws gives me access to it. That will be the first place i will check. I do suspect low refrigerant too but I do not want to over fill the system.

Make sure your condenser is clean, hose or blow it out. You really need to get the gauges hooked up. Determine the low and high compressor switch-off specs. Get it running on a hot day and feel
the low side line going into the compressor. It should be at least cool and maybe even cold and sweaty. With 134 you can allow some bubbles in the sight gauge. Do not overcharge it and go by
the old R-12 sight-gauge read of No Bubbles as the test for proper charge. If these few preliminary checks fail, you could have a dirty dryer, faulty or plugged expansion valve/tube or
impurities or moisture in the system.

Generally speaking a converted R134 system charge is about 75-80% of the R-12 capacity. Its hard to get real close without a machine or at least a scale or calibrated tank.

Red light on our 986 says over pressure. The a.c. isn't working on it either so I'll be watching to see what solutions are offered up here. Compressor won't kick on as long as the light is lit and I don't want to make more problems than necessary. Paul

I am a case/JD/MF/CAT guy but my experience with JD and IH was that the red light (tractor or combine) was high head pressure warning, generally meaning plugged condenser. At low speed that compressor can't builld the higher pressures to trip the light, but combines run WOT period. On a properly operating system that simply means a condenser issue... plugged, fan, fan belt, fan shroud, dust, debris, dirt, manure, bent fins, internal metallic contamination (no longer proper at that point). Next thing is a NON PROPERLY operating system... air flow, refrigerant flow, compressor, expansion device, deteriorating lines, contamination from oil, wrong oil, too much oil, metal from compressor, rubber from deteriorating hoses, receiver drier issues and restrictions. POssibly that that light comes on at higher speeds, from being OVERCHARGED. I am not there and I can't see it, but in every one of those I have set my hands on, tractor or combine, the red light was high head pressure. No indication for low refrigerant that I ever noticed. Check EVERYTHING. belt, fan, shroud, restriction, fins, EVERYTHING. Follow up with your findings and I bet we can assist further if you reveal something new.

condenser MUST be spotless if original to the r12 system as 134 requires (can't remember the percentage) more condenser. lots of retrofits,
mostly dodge required the condenser be swapped out for a larger or more efficient piece. I tried to avoid this on a caravan back when you
could still get 12 and at about a third of factory fill, 134 was well over 300lbs on the hi side. swapped the condenser out and could just
about see your breath on a 100+ day. jmho. fred

Just a point of information about the sight glass. When R134a was introduced, I went to a class about the
differences between the two refrigerants, working with the 134, and a host of other things including a bunch of
lies about how R-12 systems would not work with the new 134a.

In that class, we were told that the 134 would not give a clear liquid line that you could see in a sight glass.
They told us that it would always be cloudy - even if the system was fully charged. You can easily overcharge a
system by looking at a sight glass and trying to get a clear stream of liquid in it.

Gauges and a charging chart are your best guide to getting a full and proper charge in the system.