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Jared D
Jared D, ASE Certified Technician
Category: GMC
Satisfied Customers: 1863
Experience:  Shop Supervisor at County Fleet
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I'm tryingt o figure out why my ac only blows cold while I'm

Customer Question

I'm tryingt o figure out why my ac only blows cold while I'm driving.
JA: Have you checked the Freon level?
Customer: It's still blows when I slow down or stop. It's just not cold. It's not hot, but not cold. Levels are full.
JA: What is the model/year of your GMC?
Customer: 2004 Yukon 5.3L non-flex
JA: Are you fixing your Yukon yourself? What have you tried so far?
Customer: I replaced the compressor and condensor about a month ago. This just started on yesterday. Kind of noticed a freon smell inside of the cabin.
JA: Anything else you want the mechanic to know before I connect you?
Customer: no. Thats it
Submitted: 1 year ago.
Category: GMC
Expert:  Jared D replied 1 year ago.

The first thing to do should be to check the refrigerant pressure levels. Just slightly low freon on these GM 5.3l engines will make it only blow cold at higher RPM. You will be able to tell if the freon is low based on the AC high and low side pressures.

The next thing to check would be to make sure the orifice tube isn't clogged. Normally a clogged orifice tube would cause it to not blow as cold at high RPM, but occasionally these engines will only have enough compressor pressure to push past the clogged orifice tube at higher RPM.

Next, when the engine is running at an idle and the AC isn't very hot, try spraying the condenser to see if the AC suddenly goes cold. If it does after spraying the condenser then the condenser is likely clogged or defective.

Customer: replied 1 year ago.
Pressure level are at 45PSI, but I did notice an excessive amount of condensation where the orifice tube goes. I dont have a way to check the high side without taking it to a shop.Regarding spraying the condenser. Is it okay to spray plain water on it? I ask because it doesn't blow very cold when it running idle. However, this just started a day or so ago.
Expert:  Jared D replied 1 year ago.

Sorry, that wasn't clear- spray it with regular water. All you are doing essentially is cooling it off. Sometimes, especially this time of year, the condenser is also plugged up with cotton from cottonwood trees, dust, dirt, etc depending on the part of the country you live in. If you notice a lot od debris of any kind washing off of the condenser while you spray it off then that might be the cause of the problem as well.

Expert:  Jared D replied 1 year ago.

I need to call it a night. I'll check in with you tomorrow to see how the testing/cleaning goes and if you need additional info.


Expert:  Jared D replied 12 months ago.

Let me know if you still need help with this.

Please don't forget to rate.