Hello there,

My heater/AC blower will not come on when I select the higest setting, yet will work with all the others. I have replaced the blower motor, resistor and have picked up a new high speed relay, but can't seem to find where it's located. I have looked on the firewall, under the driver's and passenger's side dash, but can't locate it. If someone knows where it is, please let me know, cause my Chiltons says it's there, but doesn't say where. Thanks

 

The Berlinetta is a special case. There is no high speed blower relay located in the usual place - near the blower motor. The relays for the blower control are located in a black box (about 3" x 3" x 1"), under the passenger side dash & is screwed to the air duct work. The box has 4 relays in it - one for each speed, and they are soldered to a PC board. Chances are that either the plug in connector has coroded & needs to be cleaned, or there is a cold solder joint on the PC board where the relay is mounted. Check the plug connection to the PC board in the box & reflow all of the solder joints on the PC board & see if it works. The relay box is no longer available from GM, but may be found in junk yards. If you need to replace a relay, you may order one from Digikey @ www.digikey.com. The part number is PB104-ND, & the cost is about $3.

 

I had the opposite problem !!

I had ONLY HIGH FAN SPEED and replaced everything in the system before I finally narrowed my problem down to a poor connection. It turned out to be the Brown wire leading FROM the Blower Control relay TO the Tempature door motor.

After pulling the brown wire from the harness (at the Blower Control relay) cleaning it and setting it back in the harness,....... I had all fan speeds again.