No matter what blower speed is selected no air comes out of the vents. The blower motor is not getting any voltage. I unplugged the connector to the motor and checked for voltage there. Nada. The electronic controller is acting funny also. The lights on it seem to blink erratically. Can I assume that the controller is faulty? If so can it be repaired? Or do I have to order a new one?

Paul

 

The 88 blower motor has a relay which is located on the passenger side under the hood near the heater core. It is between the heater core and the blower motor housing. That is the first thing I'd check.

The relay is the same type used in several places under the hood (like for the radiator fans), so you could try swapping it with a known good one to see if it is the relay. If the relay is good, I'd check the connectors to the relay for voltage. If voltage to the relay is correct, then possibly it is the blower motor itself.


[Modified by Mike_88Z51, 5:29 PM 8/29/2003]

 

Manual Air has the Relay - Electronic is a little different - Which one you got?

 

I have the electronic controller. Digital display on it. The last year or so the display has been going blank, then coming back to normal after a few seconds.

 

Display is powered up by the gages fuse with memory power provided by the courtesy clock fuse. With an intermittent display, I doubt it's the fuses, but if it's completely blank now, might as well check 'em. Blower speed is determined by low voltage inputs (about 2.5 to 7 volts) from the display to the blower module on the evaporator housing. The output from module to the blower ranges from 4 to 12 volts. The module is powered up by a fusible link. Check that first - red wire at the module - should be battery voltage. Check the input voltage with the blower speed at 10 on the brown wire at the module - should be above 6 volts. Check the output voltage on the hot side at the blower motor - purple or anything other than black - should be 12 volts.

 

SunCr thanks for the reply (as well as everyone else). Sounds like you have either had this trouble already or you know quite a bit about the Corvette electrical system. I checked the power inputs to the controller, PNK/BLK wire from Gages fuse and ORN wire from courtesy/clock fuse. Both have battery voltage. Checked the 2 grounds to the controller. Both read less than 40 ohms. Grounds seem kinda funny as they all read around 40 ohms to the battery neg terminal. I dont think it's a grounding problem.

I have battery voltage to the red wire at the blower controll module. The 5 amp inline fuse from the blower control module to the blower motor checks good. I jumped the red wire to the purple wire at the blower control module plug and the blower motor ran.

The brown wire at the blower control module reads 1.4 volts with the HVAC controller set on ECON, 65 degrees, at blower speed 10. Checked the brown wire on the back of the HVAC controller and still only 1.4 volts. Purple wire on the back of the HVAC controller reads less than 1 volt. So I rang out the wires from the HVAC controller to the Blower control module. Purple and brown both read good. Less than 1 ohm through each wire.

Does the brown wire from the HVAC controller send a signal to the blower control module telling it to run, as well as the purple wire from the HVAC controller sending voltage directly to the blower motor making it run? Seems redundant?

The service manual is pointing me toward a bad HVAC controller. Any thing else I can check?

If it is a bad HVAC controller how can I get another?

Thanks

 

Sounds like the controller. Brown wire should have greater than 6 volts at the max setting. Module amplifies it to 12 volts running the blower at max. At the lowest setting, controller sends about 2.5 volts to the module which is then stepped up to 4 volts for low blower operation. You can check the low too - based on the1.5 output at high, doubt you'll see anything at low.

 

Not related to your blower problem, but for your intermittent display on your C68 climate control - maybe it’s the rear blue connecting plug. Take out the Stereo, reach behind the C68 and wiggle the plug going in the back – it’s about 2 inches wide and blue, I had to resolder all the connecting tounges to get mine to make good contact.

I fixed my C68 and everything works, it was not quite as easy as the tech tips so I posted about it - http://forums.corvetteforum.com/zerothread?id=606777

Let us know when you find out what the problem is with your blower, good hunting.

S’nut

 

Got another controller and put it in. Still having problems. This one puts out 10 volts on the brown wire with the blower speed at 10 (max). Manual says it should be about 5 volts. The blower still does not run. The purple wire has less than 1 volt. The manual says the purple wire feeds the blower a variable voltage up to 5 volts for low speed operation, and the purple wire is also a feed back to the controller at higher speeds so the controller can precisely regulate the blower speed.

I wonder if the blower mudule is also bad? Or could I have gotten another bad controller?

 

Ok - voltage above 6 volts on the brown wire from the dash controller to the module is good. Did you obtain the reading with the harness disconnected from the module or did you backprobe the connector with it hooked up? Backprobing may verify a shorted module (below 6 volts, harness connected, and then above 6 volts, harness disconnected indicates the module is shorted). Do verify the module ground. It's spliced to the blower motor ground. Follow the ground from below the blower motor on the frame up to it's splice in the wiring loom and back to the module. If ground is good, and asssembly is sending correct voltage (which it is), module is bad.

 

The 10 volts on the brown wire is with the module disconected. Voltage on the brown wire drops to less than 1 volt with the module plugged in. The module ground checks out about 20 ohms from the black wire at the module harness plug to the battery neg terminal.

I contacted vet to vet a forum vendor and they have a used module. I should expect it tomarow. The module is $526 from the local dealer. $330 from gmpartsdirect.com . Vet to vet is shipping it for $50. I just hope it is correct. He said he crossed refrenced the part number and it should be the same part as what I have. I sure hope that takes care of it.

 

Price quoted sounds like the dash controller or the programmer; not the module. AC delco show a part # 15-72530 - http://www.acdelco.com. The Last Detail - http://www.tld-corvette.com - shows a price of $95 (it's under the blower motor section in their catalog). It's been about 8 years since I bought one, it was like 80 bucks.

 

The blower module came in Yesterday. Plugged it in and now the blower works again. I guess it was not a waste to replace the controller since I was having trouble with the display anyway. I spent about $280 total. There is no saying that a shop would not have replaced both parts. At least the money I saved on labor took care of the controller display problem for me.

Thanks again for the assist. The forum comes through once again. :hurray: