Hey Kids!

Taking this fine Columbus Day off from the job for no good reason. Time to play cars!
Today's projects: -Replace A/C Blower Switch
- Replace A/C Blower Motor Resistor

Switch: Man, that is one cramped encroached area under that console. I went looking for some "Fantastic Voyage" potion to shrink down...maybe I'd find a tiny Raquel Welch in there! Could only find beer....Anyway, mission accomplished.

Resistor: I picked this up after I blew-out an O-Ring last week (the alarming sound of refrigerant suddenly venting is very special...I thought I'd blown all four tires) and noticed the blower switch only worked on "High". A Fellow Vette Fanatic in the A/C biz suggested that I replace the resistor as well....only I don't know where this critter lives.
Here's a look at it:



I hope the "EXC AC" printed on the box doesn't mean "excluding AC".

Anyone know where this goes?

 

The resistor goes in the evaporator box on top. you will see it, there is a 4 wire connector on the firewall there.

 

Thanks Danny- fellow Floridian and 49 YO-er. I'll go lookin'....(any pics of the evaporator box available?)

 

I beleive this is where it is located on my 76. Hope this helps.

 

Thanks Redman- sweet engine compartment, Man.

On the resistor front, here's what I pulled out of the arrowed region:




Very different, huh?

 

OOPS..one spring short,among other things...

You need the "AC only"

 

Eckler's to the rescue:

http://www.ecklers.com/product.asp?p...0&dept_id=1683

Thanks to all!

 

My 79 A/C fan only works on HI-speed, as does yours, but other projects have occupied my time. I'd appreciate a report on how the Eckler resistor worked. If it does the fix for you, I'll get me one as well. I'm a little south of Ecklers near Cocoa. If you aren't doing anything this Sat night stop at New Smyrna for the cruise.
http://forums.corvetteforum.com/show....php?t=1819819

 

My '81 had the same problem. For me, it turned out to be the blower relay. On the previous picture, it's the silver thing attached to the firewall just above & to the right of the arrowed resistor.

Good luck!
Dan

 

Thanks Dan, someone else told me the fix for the hi-speed only fan problem was the relay. The fix is low on my list of priorities, so it has become a 'when I get round to it' project. I'm waiting to hear how Bonedaddy has success on his before I buy any parts.

 

I have no low or high, but M1 and M2 work - any ideas ?

 

I have no low or high, but M1 and M2 work - any ideas ?

 

I'm awaiting delivery of the correct resistor- should be here end of week. I'll install it and respond on the results- ahh, but replacing the fan switch did reward me with low-med-high speeds, although the fan just doesn't seem to blow all that hard. I'm hoping replacing the resistor might help, if not, I'll proceed to the blower relay....one disaster at a time! Stay tuned!
Red 69- thanks for the heads-up on the New Smyrna show...I'll try to attend...

 

Yeah...right from the start my suspicions were that my problem was the switch, but I'm just guessing. Thanks for sharing that bit of info about your switch replacement. Since Ecklers is close by, and have all the parts I need at a reasonable price; I might just start with the switch. Once the cars get this old the parts have just worn out. Keep us posted on your results.

If you make it to New Smyrna, look for my dark red 79 and I will be parked next to a black C-4 and maybe also a black C-5. Sat ought to be nice with some cooler air. C-ya there!

 

Sorry, I'm learning with you guys. My high speed was out and replacing the relay mounted on the firewall above the resistor fixed it.

 

Bonedaddy, I might not be seeing it in the picture, but your resistor looks good to me. Those things that look like springs are the actual resistors. When they don't work, it is usually because they have burned out like a light bulb and the circuit isn't complete. I'm guessing your fan has four speeds. High is with full power. It doesn't go through any of the resistors. Low and the two mediums each go through a different resistor that reduces the power to the fan motor by using some of the power to create heat in the resistor wire. If you have all the speeds after replacing the switch then the resistor circuits are probably complete although they could have very small cracks and not have good contact. If I had a wiring diagram, I could tell you more about the relay but usually they are just an electronic switch to connect a wire with higher capacity. Without seeing a diagram I don't know why the relay would only affect the high speed. Unfortunately I'm out of town right until tomorrow night and I can't promise I'll remember to look at it. I suppose the contacts in the relay could be bad and not enough current is getting to the resistor and therefore the fan motor.

MY70. If you have low and high my guess is that two of your resistor coils are burned out. It should be easy to remove and inspect. Of course it is possible that the switch isn't making contact on M1 and M2 but it's harder to remove and inspect.

 

Hi , I have a 69 Non-AC big block, do you know where the resistor is located? I cant find it anywhere but the wiring is on the passenger side inside the car so it looks like it should be inside not the engine compartment like I have seen with A/C cars. Any help would be appreciated!

 

hi redman76! what a neat and clean engine bay you have! it is very nice! what is the cover you have over the wiper trough? did you make this or is factory? i have a 76 and water is leaking out of the bottom of the trough into the cabin floor. i hope my 76 engine bay will look that good when i'm through with it.----john

 

OK....I finally got to look into my Hi-speed only, fan problem today. Going on the information provided by forum members here, I checked out my blower motor resistor, and the coils were intact. I decided to just buy a new relay at Ecklers, but they were out of stock until the end of the month. My local Autozone had the proper relay for about $12, so I bought one. It worked perfectly and now I have all fan speeds functioning. The relay was a GP Sorensen AC11 relay, Autozone PN#156059 for those who may need to solve the same problem. Thanks to all who volunteered a helpful message and identify the broken part. Good luck to Bonedaddy whose message post proved helpful to me.