AC not working consistently

[Cynthia Grant]

(2003 St with 155K miles)



Hi! Last year my mechanic told me that the AC was not consistently blowing cold air because the AC system had a small leak and need refrigerant. He said recharging it would be more cost effective than trying to trace and fix the leak.



But soon after he recharged it (late summer last year), it still would work for a while and then suddenly switch from blowing cold air and to blowing warm, muggy air instead. After about 20 minutes, it will switch back to cold air again. The problem does not seem to be associated with how fast the truck is going. Sometimes it happens in city traffic, and sometimes on the highway.



I didn't worry about it during the winter, but now would like to know what's really going on. Has anyone out there actually fixed a leak in the AC system?



Thanks for any suggestions!

 

[Scott Tanner]

the leak is still there.. it would be cheaper in the long run to get it repaired. Refrigerant is cheap, but running it w/o the proper amount in it can cause more expensive damage, potentially. I would also check your clutch fan, as it may not be engaging 1000 at idle or low speeds, causing the pressures to go real high. i would reccommend a leak check, repair, and a full evacute and recharge. if the leak is in the compressor seal, just get a new compressor. replacing the seal is seldom sucessful.



the switch back to cold air means either your coil is dirty, and it iced up, or you're cycling on your pressure switches.



BTW, I do this for a living...

 

[scott degroot]

I don't think a leak is your issue due to the fact that it still happened after you got it recharged but I will say that any mechanic who tells you that the leak shouldn't be found and repaired does not know how to do ac work.



The main compressor control on this vehicle is the clutch cycling switch on the receiver drier. When the low side pressure drops to about 25 psi it kicks the compressor off so things don't freeze up. This would be the first thing I would look at. Other componenets of interest for this problem would be the compressor clutch relay and the compressor clutch coil. Either one of these items will cause you symptons.

 

[Cynthia Grant]

Thanks for both of your answers! I will have someone check the items you mentioned. I appreciate the help!