Hi, Im having a problem with the ac compressor not getting power in 95 blazer. I checked the fuses, the freon level is fine, and replaced the low pressure cycling switch and still no luck. I also ran a jumper to the compressor and the clutch did engage. I was thinking it may be the relay. There are three on the firewall behind the engine. Which relay controls the compressor and how can i tell if its bad? Are there any other fuses to check? Please forgive my ignorance I know very little about this sort of thing.

 

The A/C relay has 4 wires: Pink, black, white, and dark blue. Unplug the relay, turn the ignition to the run position, (do not start the engine). Select A/C on the mode switch and check the terminals in the relay socket. Pink and white should both show battery voltage. The black wire must show less than 5 ohms resistance to ground. If you apply battery voltage to the dark blue wire, the clutch should engage. Post your results for all 4 wires.

 

I don't understand the eagerness to close threads. It's never too late to add more helpful info that other Google searchers can make use off.

My A/C wasn't working at all. I purchased a tall can of 'Arctic Freeze' R134-A+ with oil & leak sealer and a simple pressure gauge & hose strapped to the can at Walmart.

I followed the instructions (leave the engine running with MAX/AC set on the climate controls). Once the pressure got up into the blue, the Compressor clutch engaged but only stayed engaged for a few seconds. It kept cycling on and off, only staying ON for a few seconds at a time. I figured that there was something else wrong, so I went online. Somebody said; "Keep adding more refrigerant.", so that's what I did and sure enough that was the answer.

If you have a cycling On/Off problem on a '96 Blazer and probably the newer ones as well, add more refrigerant until the gauge reads at least 27 psi WHILE the clutch is engaged, and the compressor clutch should start to stay engaged.

I found I needed to turn the can upside down to get all 22 oz of refrigerant into the system and it wasn't quite enough. I'm going to buy another 10-12 oz and finish filling it up until the gauge reads in the blue while the compressor is running full time.

 

A/C diagnosis & repair is not as simple as the "death kit" manufacturers lead you to believe. The system must be evacuated before charging. If not, when you charge the system with the specified amount of refrigerant, the system will be overcharged which will cause poor performance and can cause permanent damage to the entire refrigerant system. Stop leak should NEVER be added. Oil should only be added if necessary, (requires checking it). Both high and low side pressures must be monitored while charging. High side pressures vary greatly for many reasons: ambient temperature, humidity, sun load, condition of the cooling system, fan clutch, compressor, and overall condition of the HVAC system. Low side pressure must be at least 42psi for the cycling switch to turn the compressor on. When the pressure drops to 22psi, the cycling switch shuts off the compressor, the pressure rises, and the cycle repeats when it reaches 42psi. Adding refrigerant, without knowing how much is in the system, is dangerous for the system, and any bystanders. They are referred to as "death kits" for a reason

 

Viva La "Death Kit"! A '96 Chevy Blazer isn't worth professional A/C repair. I like to see one case at all of anyone getting killed by using WallyWorld "Death Kits". I got functioning A/C now thanks to my bag full of death kits. Must be a pressure relief valve somewhere cuz I couldn't over fill it. It went up to a certain pressure and wouldn't go higher.