Hello all,

I recently bought at 1999 GMC suburban. The ac has not worked for some time and I’m told it’s the evaporator core in the front. My question: Is there a rear evaporator core and will the rear ax work independently of the front if the front evap is bad? Thanks

 

If your 1999 has front and rear AC, then there is a front evaporator and a rear evaporator. But as I understand these, the only way an evaporator can be bad is (1) has a leak (2) is clogged with debris. The refrigerant is used by both front and back. Of course if the front blower motor is not functioning, then there's no air flow over the front evaporator and the rear should still operate. The front AC uses an orifice tube to meter refrigerant and the rear AC uses an expansion valve.

I'd get a second opinion on this "diagnosis", the front evaporator is inside the dash.

 

Thanks for the information. I will definitely get a second opinion on the evap being bad. I don’t really mind if it is as long as the rear works. The kids need the ac more than me ha … I’ll check the Freon this week and make sure the compressor is running. Thanks

 

You can visually check to see if the compressor is running: with engine running, AC switched on, the drive plate on the compressor (the center "disc") should be turning at same speed as the belt and outer pulley.


If the rear AC works, then the compressor is engaged (running). Low refrigerant charge can cause one area to cool and the other to put out warm.