I have a 96 S-10 Blazer that the A/C went out on. It was working properly the end of last summer, but this summer when we tried it for the first time it blew nothing but hot air. I checked under the hood and noticed that the compressor was not working. Checked fuses and relays, all ok. Then I by-passed the low side pressure switch and the compressor started working. This gave me the idea that there was not enough freon in the system to run the compressor. Put one 14 ounce can on R134A, with oil and leak sealer, in the system and it began to work correctly with the low side pressure switch hooked up properly. I checked the pressure, low side, of the system. The pressure will climb to 45 psi, with the comp. not working. And then when the press hits 45 the comp starts, and the pressure will drop to 25 psi (over a few seconds) and the comp will stop. It continues this cycle constantly.
Cold air is being blown from the vents, so from inside the Blazer, it seems to working fine.

Do I need to add some more freon? Or is this correct? Could there be another problem?

I have a 2000 S-10 and checked it's pressure and it held steadily and 45-46 psi with the compressor running continuously.

Any comments or suggestion would be appreciated.

Thanks,
MRT19

 

well im sure it has a leak somewhere in the system and I would suggest taking to a shop and having checked out to find out where the leak is as the system usually only has a few ounces of freon in the system when it is so low that the compressor will not even come on and you added a can which would still leave your system low there is usually an underhood sticker that tells you freon capacity but the only for certain way to know how much freon is in the system is to reclaim and pull a vacum on the system and then it can be charged to specifications which is why you should take it to a shop where they have the equipment to do so and to determine where it may be leaking at.

 

Bejay was pretty accurate with his response. You definately have a leak somewhere and need to find it. As for the pressures on you 2000, something is wrong there. That pressure is too high. I don't know if you gave it a chance to equalize and settle in at a running pressure or not but that should be running 30-40lbs on high blower. the pressure switch is calibrated to shut the compressor off at around 24lb and back on around 48lb. A constant suction pressure of over 45lbs would indicated either an overcharged system or a weak compressor, or maybe even an inaccurate reading gauge.