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I've got a 1997 C5 with the manual climate control system. The blower motor was going bad (high-pitched squealing that started after the drain plugs under the hood got clogged and water backed up into the cabin, coming through the carpet beside the blower motor) and so I replaced it.
Just before replacing it, I started having a glitch where there would appear to be no power to the AC control head. The lights behind the recirc/fresh air buttons would go out and none of the ***** responded. Similarly, the blower motor would cut out. After a few minutes, everything would come back and work properly again.
After replacing the blower motor, I have no lights ever. So no AC at all.
Here in Georgia, that's pretty much unacceptable. I looked at my service manual and searched the forum, but I couldn't find this particular problem, especially not for the manual AC rather than the dual automatic one.
Any ideas? I wondered about the resistors behind the blower motor, but didn't want to just replace those ***** nilly.
Whelp, checked the grounds and star connectors to no avail. Fuses also looked good, though I was lazy and didn't measure across them (they looked brand new).
I'm not sure where my shop manuals are (moved on July 1st to my first house), but I guess it's time to tear into boxes to see if I can find them.
That or start sticking a meter on everything that looks like it's connected to the HVAC.
Alright, I got behind the HVAC control head and tested from B (the red wire) to a ground (I used the passenger side courtesy light, because it was handy and colorblindness makes it a real pain for me to figured out if things are purple, dark blue, or black sometimes).
No voltage there.
Since I have no power to the control head, it looks to me like that relay has to be bad.
From what I've seen, it's supposedly above the passenger foot-well fuse box. I don't SEE it.
Before you go looking for the relay I would check out fuses 18, and 49 in the passenger foot well fuse box and also ground G202.
If those all are OK then you should look in the section of your shop manual for the HVAC for a component locator. I would hope the 97 manual has such a topic. The manual for my 04 does but has no info at all about the manual HVAC. Perhaps that didn't exist for that model year???
I did look up the owners manual for a 97 online and there is no mention of that relay in either of the two fuse boxes so at this point I have no further help I can offer on where the relay is located.
Maybe an owner of an early year car will post some additional info based on their experiences.......
I checked every fuse related to the HVAC I could find. 18, 19, 49, and even the compressor fuses, just hoping something else would magically be the problem,
The component section doesn't list the relay, but in the electronics section it EXPLAINS the relay. It just doesn't tell me where it is, as far as I can tell.
I just remembered this picture from my 04 shop manual. While it may not be completely correct for a 97, the location of the blower motor relay MAY be OK Worth a shot:
There may be more than one relay in that location above the IP fuse box so use the wire colors in your diagram above to narrow down which relay is blower motor....
Out of curiosity, where was that in your book? I didn't see anything that looked like that in mine.
Under the section of the manual about steering. Specifically it is related to the Column Lock section. The 99 and later year C5's had a Column Lock Relay (CLR) that is somewhat prone to failure. The 97 and 98 C5's do NOT have a CLR. Rather the BCM directly operates the relatively high current lock motor.
I happened to remember that there were several relays shown in that area and as luck would have it the blower motor relay is mentioned.
But as many things did change over the years the C5 was produced, you need to check and see if that is where it is located on your 97.
One of those many times when you really miss Dadaroo...
Last edited by 73Corvette; Jul 8, 2016 at 03:05 PM.
Under the section of the manual about steering. Specifically it is related to the Column Lock section. The 99 and later year C5's had a Column Lock Relay (CLR) that is somewhat prone to failure. The 97 and 98 C5's do NOT have a CLR. Rather the BCM directly operates the relatively high current lock motor.
I happened to remember that there were several relays shown in that area and as luck would have it the blower motor relay is mentioned.
But as many things did change over the years the C5 was produced, you need to check and see if that is where it is located on your 97.
So, those relays are definitely in the same place on mine. Now to try to figure out if they're the right things
Talked to a group of Corvette techs near me, and they claimed that the techs on duty haven't seen that relay fail before, and from the diagram, their best guess is that it's inline somewhere. So, fun times.
I would trouble shoot the voltages that operate the relay if it were me.
That isolates whether the problem is before or after the relay or whether your luck had the relay fail. Grounds are a major C5 problem so I would be especially interested in that. JMHO.....
I appreciate the help and input!
There're wires on the back of the HVAC control head that should have power assuming the relay is picking up. They don't.
The connectors on the back of the HVAC temperature actuator adjust **** and the directional adjust **** have power. Thereby, the **** back lighting gets power when the car turns on. And then... no power to the fan control ****.
None of the wires on the back of the fan control **** show any voltage.
None of the HVAC fuses are showing anything other than closed, as they should.
I'm... kind of at a loss if it's not wherever that AC relay is.
There have been many other threads of late where Sam's expertise would have been a big help!
Seem as though he had a schematic for EVERYTHING...usually had to wait for him to finish his beer and cigar and get home but, he always came up with it...cool dude
I found the relay, and the relay wasn't sending out power, so I thought I'd found my problem. Decided to check the input to the relay (yellow in the picture) to make sure that was the problem. Lo and behold... no power.
Moved back to blue. No power.
Pulled the fuse and measured (red) and... no power.
So, where the heck does "hot in ON" come from to the fuse block?
I'm getting ready to pull the block to see if it's a loose connection on the back of the block or something, but checking upstream again would make me a lot happier about it.
Also, should I think about making a new post for this, since it's no longer as simple as the title implies?
Took some extensive studying, but the problem was under the hood in the end!
Fuse 14, "Ignition 3/cooling" had some corrosion on it. That fuse is upstream of the brown wire that was the problem at the relay.
So if you don't have power at the AC relay under the passenger side of the car, check that fuse.
This weekend, I think I'll take the time to take pictures of every part, put them together with the manual, and try to do a write-up so that anyone else having electrical problems in the future with their AC should have some pretty good information on what to check.
AC Gremlin
