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Problems with air conditioner. Doesn't always blow cold

Hello everyone. Thanks for reading my post. I have a 1999 Jeep Cherokee and the air conditioner is giving me some problems. The issue is that at random times, it stops cooling, and just blows hot air. Sometimes I can drive all day, and it’s fine. Other times, it only blows cold for a few minutes, before the air gets warm.

I’ve started checking under the hood when this happens, and the compressor is not engaged. I noticed a couple of times that the hoses were frosted over (not every time when the compressor was out). I have found that when the air starts blowing cold, I can turn on the heater for a few minutes, and then when I turn the A/C back on, it will blow cold air again. However, often times the cold air will only last around 10 minutes before it blows warm again. Plus, there are a couple of instances where the heater trick didn’t really work.

I’ve researched this a little bit online, but I was hoping I could get a little bit more specific information here, and hopefully get a good starting point to investigate the problem. Thanks for any advice or insight you could offer!

The system might be low on refrigerant.

The vehicle needs to be taken in so the line pressures can be measured.

Until this is done, it’s anybody’s guess.


Agreed. As strange as it may sound, freezing over of the lines and evaporator are classic signs of low refrigerant. But don’t just throw in a can. Measuring pressure at the high and low ports is very important.

Asking an AC shop to checking the refrigerant ports is the place to start. IIf that’s ok, remember the physics of AC, it doesn’t really cool anything, it just moves excess heat from a place you don’t want it, to another where you do. For it to work it has to be able to remove the excess heat from the second place, and that’s done with a cooling fan in the engine compartment. If that cooling fan isn’t working correctly, this symptom could result.

A reminder that a truck compressor shop can sometimes repair a car a/c compressor much cheaper than installing a new compressor. Several years ago, i had a symptom like OP does. My son-in-law told me a friend took his car out west on Pecan to the end and right one mile to the truck compressor shop and it only cost a couple hundred dollars.

On my Sienna, replacing compressor seals, which caused the lost refrigerant, and all the related work, cost $170, not $1000 or more. That is all they do is work on the compressor and that is all that was wrong with mine. They had the seals on the shelf. They did it while I waited and read a book for a while.

I think more people need to know about this option.

Agree, the first thing is to have the pressure checked for low on refrigerant or a leak. There is a pressure switch that will disable the compressor if the pressure is too low. I’ve also had a bad pressure switch so could be either bad switch or low refrigerant.