86 high speed blower switch/relay

[Driver4]

Need help - please help me with low fan blower speed problem. Heat and A/C work fine but do not have high speed blower/fan. Was told today that switch or relay located near blower motor on fire wall could be defective. Could someone please confirm.

Thanks,

Driver4

 

[Ken]

I still don't have my books back, so I'm going from memory here...

I had the same problem where the high speed fan wouldn't work, but the low and medium settings would work. I can't remember how I did it now, but if I reversed the wires somehow, I could get the high speed fan to work, but then the low and medium settings wouldn't. :confused

I replaced the switch, the relay (which is located behind the driver information panel), but I never replaced the resisitors (located in the airstream of the blower box).

To be honest with you, I cannot remember how I got all three speeds back. It was probably in the wiring somewhere. :confused

At any rate, check the switch first, then the relay behind the driver information panel, then the resistors. I can't think of anything else to check at this point.

By the way, it's not an electronically controlled system is it? That being the case, I'd be more lost than ever.

 

[Eagle85C4]

The loss of the high speed blower is due to the ground being interrupted to the relay circuit. On mine there was a connector from the relay that was found between the exhaust manifold and the firewall on the passenger side. The black ground wire had gotten hot and was no longer making contact. I removed both black wires from the connector and crimped a new set in. Once connected back the high circuit works great.

 

[Ken]

Oh, that's right. I think mine was in the same area. Thanks Ray. :cool

 

[WhalePirot]

relay located near blower motor on fire wall could be defective

Yup, that's where it is. In HI, it gets full battery voltage at Pin D from an ORANGE wire (lower speeds pass thru resistors to Pin B; dark blue).

With: Blower Relay disconnected;
Ignition- RUN;
A/C-Vent;
Blower-HI:
Pin A is RED, from fusible link. ----Should be battery voltage.
Pin B is DARK BLUE. -----------------Should be battery voltage.
Pin C is BLACK (ground).------------Should be 0 ohms to GND.
Pin D is ORANGE.----------------------Should be battery voltage.
Pin E is BLK/RED; output from the relay to the blower motor.

Tests in the manual check for ground and appropriate voltages at the relay. Note that battery voltage is only seen at the orange wire with the swtch in HI.

The Ground, G109, is RH rear of engine compartment, on frame.

Above summarized with reference to 1987 Corvette Electrical Diag. Service Manual Supplement (8A-63, pp 0-4).

mike

 

[berky2500]

Mine had the same problem, I checked the wires, they were intact, I took the relay apart and found that a couple of solder joints from the external connectors to the relay contacts were broken. Reheated with a soldering iron, and now I have all 4 speeds.