Thread: Vents for A/C
View Single Post
Old 06-06-2007, 09:05 PM   #4
GMC Jim
Senior Member
 
GMC Jim's Avatar
 
Join Date: Dec 2002
Location: Portland, Oregon
Posts: 901
Re: Vents for A/C

GM used 2 different motors with their heater and air conditioning systems... The heater only system used a blower; specs are:-13.5 volts; 8.25 amps max; RPM 2550-2950 max. The blower used with heater/air conditioning system; specs are:-12 volts; 16.5 amps max; 3700 RPM minimum. The air cond systems used a relay which controls the blower high speed selectiom. This relay is located inside the firewall; near the top right rear of the glove box. If this relay is not operating, there be no high blower speed. This can be checked by jumping a wire from the postive battery terminal to the blower wire which should be accessible near the blower on the engine side of the firewall. If the speed ( and output) imcreases as compared to the high blower switch position on the air cond. control in the cab; then the relay is not operating. Check for proper grouinding of the relay as this is a fairly common cause for malfunction
__________________
'71 GMC;fleetside;PB/PS/AC/CC/402 Eng./Custom Paint/110,000act miles/3 fuel tanks(52gal).
GMC Jim is offline   Reply With Quote