2nd Gen Non-Engine/Transmission Poor air conditioning 'solution'

[fest3er]

Have you noticed that your A/C just doesn't cool very well when the ambient temp is over 90F or so? Mine's done that since new. But it doesn't do it any more!

What changed? Well, just before I left for Muncie, the A/C stopped altogether. I figured it was low on R134 (4. 5 years, 110K miles), so I put a few ounces in. But still no joy.

So I traced all the wiring and determined that the low pressure switch was malfunctioning. I took it off, shook it, poked at it, banged it, shook my head and put it back on. 'Lo and behold, the A/C works again. And now it cools well up to at least 95F. Driving today in temps up to 90F, I still had a couple clicks of heat to keep it from being *too* chilly.

I've driven 2500 miles now with it on and no problems as yet. I suppose I should remove some of the excess R134. I've noticed that the compressor doesn't cycle on and off any more (except after a long period of idling).

So what changed? Perhaps the few extra ounces of R134 is preventing the low pressure from dropping below the switch's cut-off value. Perhaps poking the switch and banging it loosened it up so it doesn't shut off at such a high pressure any more.

If your A/C isn't working very well in high temps, you might try changing the low pressure switch. Or just banging it around a bit. (Beat it into submission?) If that all fails, you could put an extra ounce of R134 in it. Or two. But only at your own peril.

Can one get a low pressure switch that works at a lower pressure?

Fest3er

 

[DieselDoghouse]

At worst, be prepared to shell out $20 for a new switch - I had the same thing happen, and the system would short-cycle and never cool, THEN the switch apparently hung up the other way, and without lowP cutoff I had Antartica under my dash!! New switch last summer and now I am Chillin' wit the dogz!!!

 

[jsimpson]

Any good AC shop should be able to sell you an adjustable low-pressure switch. While you're at it, vacuum the passenger floor area often, and add the inlet air filter kit from Geno's. You'd be amazed at how clogged with crud the evaporator cores are when they are pulled out!

 

[Jim Fulmer]

While you're at it, vacuum the passenger floor area often, and add the inlet air filter kit from Geno's. You'd be amazed at how clogged with crud the evaporator cores are when they are pulled out!



Just goes to show you always learn something from the board, nice web page!



I didn't think modern day women quilted anymore, figured that went away with our grandmothers.



Jim

 

[fest3er]

Hmmm. Hoist on mine own petard. Did I offer a poor 'A/C solution' or a 'poor A/C' solution? I meant the latter, but it just goes to show that even Miss Manners can trip on words now and again.



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Fest3er

 

[dvieira]

Hi. .



i give up, where's this switch at ?, what does it look like... .



thanks



dave

 

[fest3er]

Originally posted by dvieira
Hi. .

i give up, where's this switch at ?, what does it look like... .

Look behind the air filter box and down a bit. You will see a cylindrical object with A/C lines running in and out of it. This is the accumulator. On the top is a two-wire eletrical connector (green in my case). You can unplug this connector and unscrew the low-pressure switch from the accumulator.

The SM says to ensure that the switch is properly installed on the accumulator. The switch should not open until the suction (low) pressure is below about 25 PSI.

Fest3er

 

[dvieira]

A Big Thank You... . fest3er



knowledge is power, now where is my 3lb ball ping hammer!!!



again Thank You...





dave

 

[WadePatton]

and if you short the LP switch

and forget to un-short it, you'll freeze the evaporator over solid and get no air flow ATall.



Don't ask me how I know



The good news is that you can cycle the system via your dash controls and get the air going again fairly quickly... if'n you're stuck in traffic or something and this happens and you don't want to remove the jumper right there in public.

 

[Matt42]

Originally posted by fest3er

Have you noticed that your A/C just doesn't cool very well when the ambient temp is over 90F or so? Mine's done that since new. But it doesn't do it any more! -snip-



The air conditioning in mine works fine, even when it is over 115F. I've had the A/C working at 130F by the on-board thermometer. That was HOT, and it was just a few 18 wheelers & me pulling my TT on the road. Fortunately, it was a dry heat. At those temperatures, the air out the dash is about 80F, but even that feels good. By the way, it got down to 85F here last night.



The low pressure switch idea is a good one that I'll tuck away for the day I need it.

 

[jsimpson]

I added a high pressure switch to mine. No more blown accumulators!