ac major problem
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
For a/c, you need to know if it has any gas - or the right amount of gas - and there's little you can do until you know that. Hookup a Manifold Gage Set and see what's in it. Pressure should match ambient on your pressure/temp chart; ie, if it's 50 degrees out, your gages should show anywhere from 46 to 50 psi for the factory R12 fill. If you get 0 on your gages, it's all gone. You'll need to find the leak, fix it and then charge it back up. Shops have electronic leak detectors which are the best way to find most leaks - particularly evaporator leaks which are common on GM vehicles. Some do it for free because most 23 year old systems need a couple of grand of work and that's where shops make their profit. Of course most 23 year old cars aren't worth that.
For heat, you need coolant flowing through the heater core. When they plug up, the coolant flows over the top, but not through it. You can try to flush the core by removing the hoses and using a garden hose or compressed air.
For heat, you need coolant flowing through the heater core. When they plug up, the coolant flows over the top, but not through it. You can try to flush the core by removing the hoses and using a garden hose or compressed air.
Thread Starter
Instructor
Joined: Nov 2010
Posts: 241
Likes: 0
For a/c, you need to know if it has any gas - or the right amount of gas - and there's little you can do until you know that. Hookup a Manifold Gage Set and see what's in it. Pressure should match ambient on your pressure/temp chart; ie, if it's 50 degrees out, your gages should show anywhere from 46 to 50 psi for the factory R12 fill. If you get 0 on your gages, it's all gone. You'll need to find the leak, fix it and then charge it back up. Shops have electronic leak detectors which are the best way to find most leaks - particularly evaporator leaks which are common on GM vehicles. Some do it for free because most 23 year old systems need a couple of grand of work and that's where shops make their profit. Of course most 23 year old cars aren't worth that.
For heat, you need coolant flowing through the heater core. When they plug up, the coolant flows over the top, but not through it. You can try to flush the core by removing the hoses and using a garden hose or compressed air.
For heat, you need coolant flowing through the heater core. When they plug up, the coolant flows over the top, but not through it. You can try to flush the core by removing the hoses and using a garden hose or compressed air.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Blower is a somewhat different issue though it shares a Module which is also used for the Compressor ground (though '89). That Module is on the Evaporator case. You want the Tan or Dark Brown Wire which is the input. The output is whatever is hot at the Blower Motor - Black/Red or Purple. Inputs range from 2.5 volts for Blower 1, to about 6 volts for Blower 10. Output is 4 volts at 1; 12 volts at 10. If the input is there and there's no output, it's the Module - about 100 Bucks for a new one - and it's usually the culprit when the Blower doesn't work. But, make sure it has battery voltage running to it first. That's the red wire and it's from a fusible link via the Starter Motor. If there's no juice, the Link probably got fried. You'll have to jack it up and crawl underneath it to check it out.
