Air Condition


I have a 2000 GMC Jimmy 4wheel drive. After I had the 4wheel drive worked on the A/C started blowing out hot air and i put in 2 can of antifreeze in it and the lines sweats and it is not blowing cold air just hot air. CAN YOU HELP ME PLEASE


I don’t see what servicing the 4wheel drive has to do with the A/C and it really sounds like you need to have someone who knows A/C repair look at it, based on your use of the word antifreeze in referring to refrigerant.

To even make a wild guess both the high and low side pressures need to be known.
Are those sweating lines cold, not cool?
Was the system completely empty of refrigerant?
If the system was empty, then did you evacuate the system before charging?


I assume you put refrigerent in not antifreeze? The only likely connection I can thank of with the work and the A/C is if they messed up the vacuum system working on the drive. I suppose they may have don’t something to the belt or A/C clutch (wiring?).

I would suggest that if you really needed to add two cans of refrigerant, you have a problem that is not going to be fixed by adding refrigerant and if you did not get the charge correct (too much is at least as bad as too little) then you could damage the system.

I would suggest looking around first for any loose or damaged vacuum lines and if you don’t find anything that works, bring your car into a good A/C shop and let them do their thing.


This is a long shot but worth investigating. The Jimmy 4wd used to have a vacuum actuator on the front differential, I don’t know if the 2000 still uses one. If it still does then it’s possible there is a vacuum leak. If there is a vacuum leak then the blend air door won’t operate if there is no vacuum supply. So the first thing to do is to look for vacuum leaks.

Don’t be afraid to go back to the shop that did the repair and tell them what happened. They will probably recheck their work to make sure they didn’t disconnect something.


In the meantime, don’t use your AC system. If your AC lines are frosting over, that’s a classic sign of an overcharge situation. Short of having a sight glass on your system and knowing exactly how to monitor the flow of refrigerant by use of the sight glass, the only sure way of figuring a no/low/overcharge situation is to have a set of AC gauges for the specific type of refrigerant in your system. Get it to an AC shop and have them check it out including checking for a faulty vacuum system.


Hey professor… where did you learn about A/C?

The low side line frosting up is PERFECTLY NORMAL. Just about every car out there does this and there is nothing wrong with the system. It is not in anyway an indication of a overcharge condition.


Some frost is expected on the low-side line. When it builds up really thick, like in older R-12 refrigerator/freezers, it’s overcharged and will raise he77 with the whole system. It’s called a “freeze up” situation. Years of auto A.C. system maintenance, off and on though not ‘full time’, plus 20 years plus of selling and installing sub-ambient R-12 solar systems. I was an installation instructor for 3 different sub-ambient solar system manufacturers, Solar Specialties, Inc., Solar Energy Of Colorado and LamCo, all based in Colorado. We always used gauges for initial charging and operation and I showed students about monitoring the low-side system for excessive frost as the first sign of overcharging. These residential systems all had sight glasses in them also, like what Toyota had on the receiver. When the compressor in any of these systems start ‘slugging’, and you don’t bleed enough refrigerant out of the system to reduce the overcharge system, then you’ll be looking at a new compressor and most other components in a system. That’s big bucks whether a residential solar system, residential A.C. system, or automotive applications. I guess that I missed the word “lines” in my proofreading. Oh well, you caught me. The key here is excessive frosting. It could also be a number of other things like automatic expansion valve, thermostatic expansion valve, thermal-electric expansion valve, low-pressure side float, capillary tube, etc. That’s why I recommended getting his system to an automotive air conditioning shop for a thorough troubleshooting using gauges. In my view, that’s the best way to determine what problems exist.


Sorry but you are wrong. Residential A/C is not the same as automotive A/C. Frosting on the lines is not an indication of an overcharge. Maybe you need to go back to school professor and learn about automotive A/C, you can’t compare the two. I’ve been working on automotive A/C systems for almost 30 years, frosting on the lines is normal. In fact on a hot, humid day EXCESSIVE frosting is also normal.

In fact were you on this board before as STAR882? He constantly compared industrial/residential A/C systems to automotive systems.

Another thing professor, how about using some paragraghs. Rambling on like that makes it hard to read your nonsense. A smart guy like you should know how to use them.


Sweating is not frosting. Blend door sounds good. Is it possible that the heater line valve is not shutting off? Stuck coolant line valve to heater? It could just be that the heat is not turing off.


Could there be a slim possibility that when the 4 wheel drive was serviced that the A/C compressor was disconnected? It is possible.


That’s another possiblity. It could have a vacuum operated water valve and a vacuum leak could prevent it from operating.


No, willey, I have never been anybody but profhandy on CarTalk.


how about a description of the so called 4WD repair,or service.or replacement of parts ???

what was done?


To be fair to profhandy, sometimes this forum software removes all formatting… sometimes. It’s happened to me before.