whats this switch?
Thread Starter
Senior Member
Joined: Apr 2016
Posts: 733
Likes: 47
Car: 1991 base firebird
Engine: tbi 305
Transmission: 700r4
whats this switch?
its the fan speed control switch on the a/c , heat controls on the left. mine works on all but high. if its on high it might as well be off because it doesn't allow the a/c or heat to blow at all. I want to replace it but none of my searches find the actual switch or part number.
Joined: Feb 2017
Posts: 4,174
Likes: 569
From: Meriden, CT 06451
Car: 84 TA orig. 305 LG4 "H" E4ME
Engine: 334 SBC - stroked 305 M4ME Q-Jet
Transmission: upgraded 700R4 3200 stall
Axle/Gears: 10bolt 4.10 Posi w Lakewood TA Bars
Joined: Mar 2001
Posts: 10,405
Likes: 2,081
Car: '89 Firebird
Engine: 7.0L
Transmission: T56
Re: whats this switch?
The head unit in the dash is probably fine. The issue is probably in the engine bay. The first three speeds go through the head unit but the high-speed is powered by a different circuit under hood. The head unit just triggers the high-speed relay.
Joined: Oct 2001
Posts: 12,214
Likes: 1,140
From: Il
Car: 1989-92 FORMULA350 305 92 Hawkclone
Engine: 4++,350 & 305 CIs
Transmission: 700R4 4800 vig 18th700R4 t56 ZF6 T5
Axle/Gears: 3.70 9"ford alum chunk,dana44,9bolt
Re: whats this switch?
Qwk is correct, a couple things to look for on the high speed circuit.
I've seen the power wire connector (under hood) get hot and melt due to a bad connection (between HAVC box and pass side of motor) and I've seen the blower relays fail.
I've seen the power wire connector (under hood) get hot and melt due to a bad connection (between HAVC box and pass side of motor) and I've seen the blower relays fail.
Thread Starter
Senior Member
Joined: Apr 2016
Posts: 733
Likes: 47
Car: 1991 base firebird
Engine: tbi 305
Transmission: 700r4
Re: whats this switch?
thanks for the replies guys. I will have a look under the hood and see whats melted. hope its something I can find easily. if I understand this correctly fixing the high speed will NOT change the way the other 3 speeds work? its not going to make each speed stronger?