heater air blower speed control
Thread Starter
Drifting
Joined: Oct 2002
Posts: 1,818
Likes: 13
From: ar
heater air blower speed control
can any one help me locate the problem with the blower speed on my 1977, it will only blow at high speed . when you move the switch down it shuts off . It blows high in all positions-heat -defrost - air - vent. I have tried a new switch with same results. any help would be apreceiated.
Drifting
Joined: Aug 2002
Posts: 1,731
Likes: 22
From: Marietta Ga.
Re: heater air blower speed control (silverslashstreak)
The following is from a previous post. There is a blower motor high speed relay you can check for good connections. My 73 has a/c and the relay is located on the side of the a/c box. Not sure where the relay is located on cars w/o a/c.
This relay has a conector with several wires going into it. Two of the wires are fatter than the others. Its purpous is to create a direct link to the bat for high speed blower mode. The relay is used because the dash mounted switch would not be able to handle the high voltage of the high speed setting. On my 73 the high voltage lead for the blower is fed from a junction all the way over on the driverside inner fender. when you put the blower switch to the high position, the lower amp(thinner wires) leading to the relay open the circut for the high amp high speed blower setting. since all of these wires are associated with blower operation, I suppose any one of them could be causing a failure.
It sounds like your relay is at fault. Check in archives and at corvettefaq for other info. Hope this helps
:seeya :seeya :seeya
This relay has a conector with several wires going into it. Two of the wires are fatter than the others. Its purpous is to create a direct link to the bat for high speed blower mode. The relay is used because the dash mounted switch would not be able to handle the high voltage of the high speed setting. On my 73 the high voltage lead for the blower is fed from a junction all the way over on the driverside inner fender. when you put the blower switch to the high position, the lower amp(thinner wires) leading to the relay open the circut for the high amp high speed blower setting. since all of these wires are associated with blower operation, I suppose any one of them could be causing a failure.
It sounds like your relay is at fault. Check in archives and at corvettefaq for other info. Hope this helps
:seeya :seeya :seeya
Heel & Toe
Joined: Oct 2002
Posts: 20
Likes: 0
From: bradenton fl
Re: heater air blower speed control (silverslashstreak)
i'm no corvette expert but in GM cars there is a set of resistors that are mounted in the heater box. They are mounted in the heater box as to have air blow across them to keep them from burning up. They are all conected together with a wire connection going to the group. Each resister controls a different fan speed and there is no resister for the high speed. thats why high speed works and no other speed. either the resisters are all bad or just unplugged. i have had this problem in several gm cars and it is an easy fix.
Melting Slicks
Joined: Oct 2000
Posts: 2,143
Likes: 195
From: Englewood FL
Re: heater air blower speed control (silverslashstreak)
Since the fan is only working on high speed, the problem is most likely
the high speed blower relay. If the resister were bad, then certain
lower speeds would not work, as there are separate coils for each
fan speed.
The high blower relay is mounted on the firewall near the blower
motor resister (toward the passenger side from the distributer).
the high speed blower relay. If the resister were bad, then certain
lower speeds would not work, as there are separate coils for each
fan speed.
The high blower relay is mounted on the firewall near the blower
motor resister (toward the passenger side from the distributer).
Melting Slicks
Joined: Oct 2000
Posts: 2,143
Likes: 195
From: Englewood FL
Re: heater air blower speed control (silverslashstreak)
Would try a new relay. As a temporary fix you can remove
the cover from the existing relay and clean the contacts.
Then have some one switch between high and the lower fan
speed settings and see if the relay moves. If not, try
spraying some wd 40 to free it up. If you can get it working,
this will at least prove that the relay is bad. Would then
replace it, as I have found that the cleaning and lubing is
normally only a temporary fix.
the cover from the existing relay and clean the contacts.
Then have some one switch between high and the lower fan
speed settings and see if the relay moves. If not, try
spraying some wd 40 to free it up. If you can get it working,
this will at least prove that the relay is bad. Would then
replace it, as I have found that the cleaning and lubing is
normally only a temporary fix.
Racer
Joined: May 1999
Posts: 268
Likes: 1
From: CT
Re: heater air blower speed control (silverslashstreak)
If your high speed relay was at fault your fan would work on all speed settings except for the high speed. It sounds like you need to test your resistors that are mounted in the heater box. It only takes one resistor to blow for all of them to stop working, depending on which one it is. This is because for low speed the power runs through all 3 of the resistors and only 2 for your second speed and only one for your 3rd speed. At least this is how most older gm cars are set up. Hope this helps
Kevin
Kevin
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Le Mans Master
Joined: Sep 2002
Posts: 9,386
Likes: 0
From: 30 mins north of Charlotte NC
Re: heater air blower speed control (71vettman)
i had the same problem
well the fan worked only on high with the ign switch turned to acc, but when you turned to on the others worked,,,,
turned out the ground for the fan was attached to a hot wire at the starter(dont ask,,,,i bought the vette from bubba) and my fan only worked on high, i guess the relay acts as a ground,,i dont know,,,,,did you buy your vette from the same guy :rolleyes: :rolleyes: :rolleyes:
[Modified by Titanium Rat, 7:55 AM 10/18/2002]
well the fan worked only on high with the ign switch turned to acc, but when you turned to on the others worked,,,,
turned out the ground for the fan was attached to a hot wire at the starter(dont ask,,,,i bought the vette from bubba) and my fan only worked on high, i guess the relay acts as a ground,,i dont know,,,,,did you buy your vette from the same guy :rolleyes: :rolleyes: :rolleyes:
[Modified by Titanium Rat, 7:55 AM 10/18/2002]
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
Re: heater air blower speed control (Titanium Rat)
Titanium, you got something there, if that silly ground wire is connected to the battery post, it's likely to get most anything as a result...normally that heater blower will run backwards though....polarity reversed....
and of course that early shark WSW motor is grounded through the same wire...dunno about later sharks...
when I rewired my car, I moved that connector tab to up top to t he intake manifold where it belongs....
GENE
and of course that early shark WSW motor is grounded through the same wire...dunno about later sharks...
when I rewired my car, I moved that connector tab to up top to t he intake manifold where it belongs....
GENE
Intermediate
Joined: Oct 2002
Posts: 45
Likes: 0
From: Kirkkonummi
Re: heater air blower speed control (Titanium Rat)
i had the same problem
well the fan worked only on high with the ign switch turned to acc, but when you turned to on the others worked,,,,
turned out the ground for the fan was attached to a hot wire at the starter(dont ask,,,,i bought the vette from bubba) and my fan only worked on high, i guess the relay acts as a ground,,i dont know,,,,,did you buy your vette from the same guy :rolleyes: :rolleyes: :rolleyes:
[Modified by Titanium Rat, 7:55 AM 10/18/2002]
well the fan worked only on high with the ign switch turned to acc, but when you turned to on the others worked,,,,
turned out the ground for the fan was attached to a hot wire at the starter(dont ask,,,,i bought the vette from bubba) and my fan only worked on high, i guess the relay acts as a ground,,i dont know,,,,,did you buy your vette from the same guy :rolleyes: :rolleyes: :rolleyes:
[Modified by Titanium Rat, 7:55 AM 10/18/2002]
Le Mans Master
Joined: Aug 2001
Posts: 7,804
Likes: 4
From: Standing still with all my might Texas
Cruise-In X Veteran
St. Jude Donor '09-'11
Re: heater air blower speed control (Titanium Rat)
(dont ask,,,,i bought the vette from bubba)
I installed a good resistor and the blower works fine, Go figure :D
