A/C blower question
Thread Starter
Le Mans Master
Joined: Feb 1999
Posts: 6,470
Likes: 2
From: levittown pa. usa Even a bad day with my `Vette, is better than a good day at work
St. Jude Donor '10
A/C blower question
A/C works fine, but (there`s always a "but" ain`t there? 
) the fan only works on high speed, no low speeds. Also, after running at high for a while, the fan just cuts off, like a relay overheats. This is a manual A/C setup. What am I looking for??
) the fan only works on high speed, no low speeds. Also, after running at high for a while, the fan just cuts off, like a relay overheats. This is a manual A/C setup. What am I looking for??
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
I agree with Scorp - remote possibility that it's the dash panel which contains the Blower Switch (sometimes you can just replace this part too). First three positions are fed from the panel through the Resistor Pak - Max is a direct shot from the panel to the Relay which then feeds battery voltage from the fusible link to the Blower. If you want to check the resistor pak, measure ohms (ignition off) between A & C, C & D and D & B. A & C should be about 1.5 ohms, C & D .7, and D & B .2 ohms. To check the blower switch, put it on low and there should be battery voltage on whatever colored wire goes to C on the Resistor Pak.
Melting Slicks
Joined: Aug 1999
Posts: 2,240
Likes: 41
From: Baltimore, MD USA
The Blower Relay is used to supply voltage to the Blower motor in any speed.
Hi speed uses the normally open relay contact.
The 3 lower speeds use the normally closed contact.
If you're having problems with all of the speeds,
most likely the relay is bad. Replace the relay or look for burnt wiring or contacts on the relay socket.
Could also be your Blower Motor is going bad. When it's on high speed and it stops, disconnect the plug at the blower motor and measure the voltage going to it.
Hi speed uses the normally open relay contact.
The 3 lower speeds use the normally closed contact.
If you're having problems with all of the speeds,
most likely the relay is bad. Replace the relay or look for burnt wiring or contacts on the relay socket.
Could also be your Blower Motor is going bad. When it's on high speed and it stops, disconnect the plug at the blower motor and measure the voltage going to it.
