Hello Everyone. It's been a while since I was here. I have a 1990 FSB 5.0 with 5 speed manual trans. My problem is that whenever I turn on the A/C or Defrost the Bronco stalls when running at idle. On the highway the A/C and Defrost work fine, but slow down in traffic or to make a turn and it stalls. This is especiallly fun when turning from a highway down an off-ramp and it stalls. Any ideas?

 

When was the last time the IAC was cleaned really well? If the computer gives you no error codes during a KOEO or KOER test, the most likely problem is cruddy idle air passeges in the IAC (Idle Air Control solenoid/valve).

 

My 89 was doing the same thing. There is a "solenoid" on the throttle body that increases the idle when the a/c kicks on. Mine was bad. I got the replacement at Autozone. I am not sure what the exact name of it was but I believe that it was either the Idle Air Control (IAC) or Bypass Air Idle Speed Control. It is below and behind the intake "tubes" and has a couple wire plug on it. Page 4-25 if you happen to have a Haynes manual.

 

Yep, the IAC is sometimes referred to as the BYP-IAS or (Bypass Idle Air Solenoid). Replacement isn't always necessary though. It gets filthy in there and can be cleaned with throttle body cleaner and reinstalled using a new gasket between it and the throttle body.

 

Oh by the way where can we get the gasket alone?

Thanks

Mike

 

You can't....at least not to my knowledge. You can cut a new one from gasket paper which is often cheaper than buying a new pre-cut gasket anyway. You will end up with a LOT of leftover gakset paper but you can always cut thermostat gaskets and more IAC gaskets from it later.

 

just unplug the ac pump at least youll be able to defrost your windshied untill you can fix it properly

 

check the ac pump grab the very front of the pump (engine off) and turn it if it doesnt turn the pump is locked up and time for a new ac pump unplugging the pump will keep the clutch from ingaging and alow it to turn if the pump is locked the iac or anything else is not going to help