Hi all
I have got 1998 blazer. There is a weird problem. When I am driving on the highway the ac seems to work all fine. But if I am in the city the ac compressor stops working and the temperature of my blazer goes above 100C/212 F. Usually the truck's temp stays a little below this. When i get let it cool down and get back to the highways the ac starts working fine. Got the gas checked and everything was fine. Someone said that it might not be the compressor problem. So not sure what could it be.
Help!

 

Could be a problem with the fan clutch, debris in front of the condenser, weak compressor, low on refrigerant. What are the cycling pressures, both high side and low side?

Keep in mind, it is impossible to check refrigerant level on a clutch cycling system by checking pressure alone. The ONLY way to know how much refrigerant is in the system is to drain, evacuate, and recharge the system with the proper amount of refrigerant.

 

Yeah, I'm betting it's your fan clutch. If it spins freely it's time to replace it.

 

I took it to the workshop and the ppl ova there told me its not the gas pressure. Everything seemed to work fine when I was there. Even the compressor wouldn't turn off. Damn sly Ac..lol... So later on one guy told me it is possible ur magnet inside the compressor is not working. Is that what the fan clutch is? How can I get it replaced? Do i need to have the compressor opened up? The cost of the compressor ova here is around 240 $ a bit expensive for me rite now. Don't wanna take risk either. Wat if its not the compressor rite?

 

Fan clutch and compressor clutch are two different things.

If the compressor wouldn't turn off, there's a problem. Either the clutch is seized to the compressor shaft, (doubtful) or the refrigerant charge is low, the clutch field is getting voltage all the time, or the low pressure switch is faulty.

"Magnet inside the compressor not working", there are no magnets inside the compressor. When the clutch field is energized, it creates a magnetic field that engages the compressor clutch. When the clutch is engaged, it connects the pulley with the compressor shaft.

What are the cycling pressures, both high side and low side, when the compressor turns on, and when it turns off?

 

The thing is I didnot read the pressures myself and took the word of the mechanic. He said both times with and without the compressor they showed a proper pressure. So I can't say anything abt its pressures. He had also cleaned the radiator which kept the compressor running longer than usual though.

 

Perfectly normal result... the condenser can flow air through it easier to get rid of the heat. As a result, the compressor will run longer. Really need the pressures to get an idea of what's going on with it though.

 

I will see what I can do for the pressure readings. Any specific instructions that I should give them for the readings??

 

High and low pressure readings plus the ambient (outside) temperature during the testing

 

As 1998MSO mentioned, we need ambient temperature, also, engine at operating temperature, 1500RPM, windows and doors closed, AC set on MAX position, fan on high speed... allow system to stabilize...

High side pressure when compressor turns on.
Low side pressure when compressor turns on.
High side pressure when compressor turns off.
Low side pressure when compressor turns off.
Center register temperature.