Topic: no fan!!
in Forum: C3 Cooling and Heating Systems
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hi all...proud new owner of a light blue 77....
Started eveything up today to check it out noticed that when I turned on the heater that the mtor wasnt blowing!
I heard a hissing from the unit bt no air coming out of the vents.
Any help would be great!
John
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Duncanville, TX - USA
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Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
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#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
Did you try ALL of the blower speeds on the switch? The lo/med/med hi speeds all work off of a resistor in the heater core plenum(box), but the High speed works off of a relay. If you do not have a working blower motor on ANY speed, you may either have a bad blower motor, or a wiring problem. Try checking the connections at the blower motor to make sure the two connection(power & ground) are good. The, you may want to check for voltage at the purple wire on the blower. If you have varying voltage at the wire with the switch on the different speeds settings, then your motor is not good. If no voltage, it's time to start checking out the wiring, and circuitry...
Joel Adams
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Thnak you very much for your response!
I've tried all speeds and nada!!
When I move the slider from the off position to vent/defrost ect... all I hear is hissing.
I will trouble shoot with all that you have mentioned.
thanks again!
John
Lifetime MemberLemon Grove, CA - USA
Joined: 10/17/2007
Posts: 2041
Vette(s): 1982 C3 Collectors Edition 44000 miles, sat in the sun most of its life, My wife purchased it for me for Father's Day in 2007 from her girlfriend that had it for 19 years. It is on the road again. I'm retired but it is now my daily driver.
Adam is that the same set up on the switch for 78-82? with the high speed taking a different path than the lower speeds?
Lifetime MemberManteca, CA - USA
Joined: 11/20/2005
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Vette(s): 1978,two tone,Metalic Rootbeer & gold
1975 L48 4 speed
and the hissing is vacuum leaks. Usually old, missing or disconnected hoses under dash or upper console.
Jimmy B.
Just can't wait to get on the road again. 
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Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20214
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
tb2k82ce said: Adam is that the same set up on the switch for 78-82? with the high speed taking a different path than the lower speeds?
Afaik, Gilbert, all GM products of the era with A/C had the same type system, as far as the high blower goes. It always runs thru a relay. If it did not, the wiring would loose all of the smoke, and the switch would melt from the high amperage. This is why the high speed blower relay is mounted fairly close to the blower motor.
Joel Adams
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Cramerton, NC - USA
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Vette(s): black 1982 coupe slate gray interior, 350 crossfire, 1985 fuel pump, Steeroids R&P conversion
It sounds like you may have at least 2 different problems. The blower fan is electric and operated from the switch, resistor and relay as Joel mentioned. The hissing part of the problem is probably from the vacuum part of the system which operates the blend doors which route air to different areas dependng on where you move the sliders for defrost, heat, a/c etc. Lots of vacuum hoses attach to the control console. The only way to know where the hissing is from is to remove the side panels and have a look / listen.
I was going to post a similar problem but I'll ask here if I may.
I have no low or low/middle fan speed; only high/middle and high speed. The car is a '75 with air conditioning. I would appreciate ideas on where to look. It was working last summer before I rebuilt the contols with a new faceplate and roller wheels.
Greg.
2012101154624r.jpg)
Build Date: May 7, 1975. 383 w/267 RWHP/310 RWTQ
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Cramerton, NC - USA
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Vette(s): black 1982 coupe slate gray interior, 350 crossfire, 1985 fuel pump, Steeroids R&P conversion
Case75,
The first thing I would try is to locate the resistor in the heater air plenum (see pic) and one by one, pull each wire from its connector then reconnect, then move to the next wire and do the same. I have found that sometimes corrosion can cause those connections to fail. If that makes no difference, it may be the switch itself on the inside console. If the highest and lowest speeds are working I think the relay is working as it should, somebody correct me if Im wrong. The location of the resistor and relay may be a little different on your year vette.
Thanks Crossfire for the pic. The relay and resister are in the same place on mine. I'll give that a try. If I number the fan positions 0,1,2,3,4 with 0 being off, it is position 1 & 2 that are not working.
Greg.
Build Date: May 7, 1975. 383 w/267 RWHP/310 RWTQ
in Forum: C3 Cooling and Heating Systems
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