AC temp adjustment thermistor?

[belted_guns]

It is hot in Texas. Is there a AC temp trigger adjustment? There are no knobs. Just on or off. Can the set point be adjusted? Asking about the newer 115x trucks.

 

[Autonomy_Lost]

No. But you can do what I did and replace the electronic heater valve (i forget the technical name) with the cable actuated one from an m998. Then you can add however much heat you want.

 

[Retiredwarhorses]

It is hot in Texas. Is there a AC temp trigger adjustment? There are no knobs. Just on or off. Can the set point be adjusted? Asking about the newer 115x trucks.

adjustment? They don’t blow cold enough…

 

[belted_guns]

True enough. It just seems that the compressor kickin could be at a lower temp and stay on longer. Even in the 100+ degree weather, the compressor goes on-off. It is that trigger point i was wanting to change. Is there a thermistor or some temp controlled solinoid that can be mucked with to lower the "turn on" temp, and the "stay on" until the temp drops below that temp? The dang thing turns on for less than a minute, then off, then waits, then on, then off. but the internal temp of the cabin does not change temp. - I get the full capacity is not enough, then just stay on?

I was not clear in my earlier post, sorry.

 

[Mogman]

There is a low pressure switch on the compressor suction side that would cycle the compressor off early if the freon charge is low, there is also a thermostatic switch in the front evap in case it gets too cold which does not seem to be your issue, are you sure you have a full freon charge?
Also if your condenser fans are not running or the condenser/s are dirty that could cause the compressor to cycle

 

[belted_guns]

thanks all for the quick responses. I will check the pressure in the system and see if the fan is running. should be above 105deg today, so plenty warm enough. I did "check" the pressure before but of course you all are correct.

 

[Mogman]

Looking at the schematic it looks like at least one set of condenser fans would cycle with the compressor if ether the temp was too cold or the low pressure switch kicked in, if the high pressure switch was activated only the compressor would cycle, this would indicate ether the system was over full or the condenser/s were not doing its job for what ever reason or a possible restriction in the system.

 

[belted_guns]

I am not an AC guy. I put the pressure meter on the AC, started up, got 70+, then when the compressor kicked in, it went very low. So, I guess I need to add some fluid and perhaps watch for a leak.
When the engine is off, the pressure reading is 70+, which reads high for civilian vehicles.
Anyone know which manual would describe the proper AC fill, fluids, readings?
Mogman, thanks for that schematic. I printed it off.
the 387-10 does not speak to maintenance of the AC or what it takes

 

[Mogman]

Fans on high 1500-1700RPM
This is just a ball park chart but it should be close.

 

[Mogman]

If the numbers are off and adding a little does not start the needles going in the right direction then do not add any more.
The pressure when not running is insignificant, it's like liquid propane the sitting pressure is entirely dependent on temperature.

 

[belted_guns]

ok, thanks. more information. I used r134a, tried to add with the compressor running. seemed to make a difference but very little was added by weight. though now the compressor stays on - it is a stagnant 107 right now
other pieces of information.
1) the fan is a gear driven and it is on
2) the aft blowers are on
3) i only get cold air from the right side front passenger vent. there are two vents on the front passenger side, the right side (closest to the door) is blowing cold air (the left side front passenger vent is blowing warm air). all other vents are blowing warm air, including the rear passenger box in the middle. all those are warm air.
Strange. it is almost like the front air ducking on top of the bottom metal dash has two channels. could that be the case?
However, that does not fix the back seat box. is there a separate compressor system for that?
(or i have shit for pressure and i need to fix that)
My cheap autoparts store pressure gage is reading about 15psi with the compressor running. according to the chart, that is loooww.

All things considered, at that pressure, should i be able to empty that can of 134 into the system? perhaps my cable is bad?

 

[Mogman]

Try to add some more and bring the pressures up it does sound like it could take another 12oz, but only add about 1/2 a can and let it settle out, your heater valve may be inoperative causing the vents to blow hot air although it is a mystery why some are cold.
When I said fans I meant the evep fans.
Do you not have a high side gauge?, is the gauge you have one of those that comes with a can of 134A for the low side only?
From where you live I bet there is a Harbor Freight near by, even that cheap R134A gauge set is much better than nothing!
And the high side is more important to monitor than the low side.

 

[belted_guns]

SUCCESS!!!, thanks for the absolutely excellent information. RCA was low refrigerant, then it was a bad low pressure hose for the refill bottles. Once I got a new hose and better gage, took 3.4 12oz bottles of r134a to get it up to about 51psi in 106deg. Cool air flowing out of all the vents, compressor stays on, vents stay cool.
Thanks for those diagrams, all very helpful.

 

[Mogman]

I would still invest in a full set of gauges to make sure the high side was within range, the entire system only takes 4.6 cans of 12oz R134A
CHEAP insurance.

One of the problems with a system that sits for years is the compressor shaft seal dries out so you may not be out of the woods yet.

Also if it was that low and if it were me I would invest in a new drier and have the system evacuated completely then refilled, the difference in the life of a system with a little moisture and one with no moisture can be decades.

 

[belted_guns]

Mogman, good ideas. I will put that on the list to get done. My next immediate action item is changing the rotors and brake pads. After i took delivery of the 1151, I found a maintenance tag from Dec 29, 2021. I bought it Dec 2022. It must have been recently decommed.