Aloha from Hawaii! My baby is a 4-door 2000 4WD Blazer and I love her... thing is, the A/C will blow warm air instead of cold, and as far as I've seen, it has nothing to do with time of day, outside temp, idle, speed, etc. It starts off either warm or cold, and after several random minutes it will switch. May not seem like a big deal to those on the continental 48, but in Hawaii it's pretty much hot & humid all year round. The Blazer is stock, I only use 87 octane, and keep her topped off on the oil and coolant. I think I read some time back something about an O2 or pressure sensor... anyone else have this problem? Is there anything else I should include?

I checked for A/C problems in the search bar and found nothing really describing my problem after searching 12 pages.

 

Welcome to the forum. We get rain and snow and you get the earthquake, hope all is well there.
Chances are you are low on refrigerant. Have a look at the front of your A/c compressor for any signs of oil (sometimes a thin line of oil is thrown on to the inside of the hood) Check for oil leaks along the a/c lines and pipes, specially near any connections at the condensor or accumulator. Oil leaks usually show up as black due to mixing with dirt. If there are oil leaks from the a/c, then your refrigerant is low for sure.
It could have enough refrigerant to work for a while until the low pressure cycling switch cuts out the compressor.
Unless you have the pressure guages, I recommend taking it in to a shop for testing and service.

 

Ah, thanks for the fast reply... I had no idea how to check the A/C pressure, and I didn't want to just add 134a because I was hearing something about too much refrigerant being a possible cause. I'll be popping the hood today... just curious though, I've seen the gauges to read A/C refrigerant pressure at local auto stores, should I pick one up versus taking her into the shop?

In any case, everything here is fine, nobody got killed and the people who are b!tching about the power not coming on sooner were the ones who were expecting the geovernment to save their butts. I had a case of water and a grill in my Blazer... the people here need to live up in the northeast and deal with storm-related power failures to appreciate how good the have it here!

 

I'm not sure how much a set of guages will caost you, but there is a quick test you can do without guages.
Warm up the engine and go to "max a/c". Check the temp of the pipes at the accumulator, one should get warm and the other cold.
The a/c compressor should cycle on and off but not to quickly. If the a/c clutch just kick on and off, on and off, then you're probably low on 134a. Just remember that if you're low, it probably has a leak in the system.
I can send you the pressure specs if you feel competent and want to buy a good set of guages, but I just wonder how often you would have to use them.

 

Thanks... I hit Checker today, came close to picking up the Chilton's for my truck-- I guess that would be a good investment. They had the UV dye there as well as the leak sealer, but I will try what you said before I start pumping stuff into my system... thanks for all the help!

 

Let us know what you find, it might help someone else too.

 

Wow, now the A/C is working just fine... I can't get the problem to start up again! I guess that's a good thing...