2nd Gen Non-Engine/Transmission Erratic Air Conditioner

[cwsoules]

My air conditioner will sometimes cool properly and then start blowing uncooled air. When starting the truck it often will cool properly but after driving a while it will quit. At 60 mph soometimes I get cooling and sometimes not. I believe that there is a clutch which activates the A/C when I turn it on. It seems that the clutch or the controls of the clutch are bad. Any ideas?

 

[J Shocik]

I looked up some older threads on this problem, as I had the problem with my truck. The clutch engages for a few seconds, then disengages, on and off. The most common cause for this problem was low level of 134a. When the system is low, the low pressure switch shuts down the A/C. When the clutch shuts down, the 134a pressure rises, turning on the A/C, which lowers the pressure, which shuts down the A/C, which raises the pressure...



I bought a 134a recharge kit, followed the instructions , and got it working again. If your system is just low, this should work.

 

[Mr. C]

What J Shocik said. One thing to add is be sure to NOT use the refridgerant with leak sealer in it, you may have to buy a extra can to get straight R134a most recharge kits include a can with sealer mixed in so read the lablel carefuly.

 

[Stake Man]

We have had this problem since day one with our truck. The R134a just dissapears. Dealer charges us $78 for an hour of diagnosis and then the refrigerent. Recently, never finding a leak. Even though its been 3 weeks since the last recharge and its dead again. They did add a sealant to the system. When I confronted them about the TSB about not doing it..... "Its okay for us to do that now" But now that the truck is completely out of warranty, "The whole system has to be replaced cause WE(as in us, the owner) put a sealant in the A/C system. " Never am I going back to that dealership. I'll drive the 1. 5hrs to the next nearest one.

 

[JohnMcIntyre]

Don't forget the pressure and vacuum tests!!

My air conditioner will sometimes cool properly and then start blowing uncooled air. When starting the truck it often will cool properly but after driving a while it will quit. At 60 mph soometimes I get cooling and sometimes not. I believe that there is a clutch which activates the A/C when I turn it on. It seems that the clutch or the controls of the clutch are bad. Any ideas?

The responses you have so far are all equally valid, but here's something else for you to think about as well.



When the AirCon tech hooks up his diagnostic equipment before recharging the system with new R134, they should be performing a vacuum test for about 20 minutes. This is however, only half of the story - yes that will pull down on all the seals and then the vacuum should hold, but when you get it refilled, the problem of intermittent cooling can easily return.



One reason for this is because the R134 is put into the system under pressure (rather than vacuum!), it will leak past the same seals that were pulled down under vacuum. The best way to verify the integrity of the scomplete ystem is to not only complete a full vacuum test but also get the AirCon tech to add a fluorescent tracer die to the R134, so if you have any leaks, which sounds probable to me from your explanation, then a regular UV light under the hood will nail this for sure.



More importantly if they fill you up with R134 and you tell them upfront that you suspect a leak, if they don't put a tracer die in with the gas and it escapes, you should not have to pay for the subsequent refill, if they are a reputable AirCon service station.



BTW, when you pop the hood there's a sticker just in front and to the left of the radiator on the sill which tells you how much R134 should be in the system. (typically 0. 909Kg). Worthwhile asking the AirCon tech how much they were able to retrieve/scavenge before they start the vacuum test. better still, if they let you observe this in action, so much the better... .



Hope this helps!