fast69cam

I have a 71 Vette (350 / 270hp, with a/c) that I have replaced the blower fan switch, the blower motor cutout relay, the main control in console, new engine harness, a/c harness, front wiring harness, but I still have no "high" speed on the blower fan.

I bought another piece, the blower motor resistor ( see this link for picture -

http://www.zip-corvette.com/ProductDetails/ProductDetails.aspx?pid={47db8b56-6c89-413f-9427-cbe240fb5251}&pname=63-79+Blower+Motor+Resistor&Referer=QUICK_S EARCH&Alias=1971%20blower%20relay&ptct=B S-SR&CTitle=&

but I cannot seem to find where this part actually goes. Can someone please let me know what else to check or what my problem may be ?

Thanks in advance...

Ronnie

71coupe454

I have a wiring diagram if it will help you. That part is what you need to fix the blower.

fast69cam

Did you look at the part I had in the posting ? If so, where does it go ? It is not the relay on top of the air box, I cannot figure out where it goes... I have a wiring diagram but it does not tell where the part is located. Let me know once you have looked at it. Thank you very much !!

CCrane65

Ok, I'm not being a smart a$$ here but did you check the 30 amp fuse on the horn relay? That is specifically for the high speed blower operation.

cc

fast69cam

.. absolutely no offense taken... I can check it again but it was brand new - part of the new wiring harness I installed. I put a new fuse in it when I put it in. I did not replace the horn relay - could this be the issue ?

CCrane65

I doubt it. As long as the post the fuse wire is connected to is hot that's all the relay does for the blower. And if your horn works then the blower should too.

If the fuse is good then it is likely the resistor in the top of the air box as mentioned previously.

cc

7T1vette

If there's a short in the wiring for that "Hi speed" blower fuse, a 'new' one will still blow immediately. Remove the fuse and check for continuity. If 'bad', find the short in the wiring and repair it. If 'good', you have an open circuit somewhere in the wiring or no power (+12v) going to the fuse.

mds3013

If you are still looking for where it is installed here is a picture of my '77. I do not know if yours is in same location but all blower resistors will be located in the "duct" where air flow will cool the coils. mds...

...Roger...

Is the blue wire going to the relay getting 12 volts when the switch is in the high position "AND" is the relay grounded ?

edit-the high blow bypasses the resistors

CCrane65

You do have 4 wires on the blower relay right? One black, one blue, one orange (12 gauge) and one purple (12 gauge).

The wires are connected in the following order as you are looking at the bottom of the relay:

Black


Purple
Blue Orange

You should have the bottom three wires in a single connector but mine was missing so I offer this information just in case.

cc

...Roger...

But make sure the other end of the black wire is grounded through the blower ground.
wiper,relay,blower all ground together through the black at the starter.

oldsarge

the resistor is under your dash behind your radio area, screwed into the heater box ductwork.

Peterbuilt

My plug that goes to the (relay) in the top of the picture, is melted. Where can I get a new one?

...Roger...

http://www.autozone.com/autozone/cat...andName=Dorman

Peterbuilt

Thanks, that was to easy, hope fast69cam's problem can be fixed so easy!

fast69cam

OK, I've checked and the fuse is good AND I have positive current coming from the orange wire coming from the horn relay. Is there any thing else I can check ?

fast69cam

If this resistor is bad, will it effect the "high" operation of the fan blower motor ?

7T1vette

No. The resistor pack is not in the circuit when the blower is on "High" speed. If there is power to the 'input' side of that fuse, that means the blower switch and wiring up to the fuse are good. Your problem must be between the fuse and the blower motor. That leaves just the wiring between them and the blower relay. My bet is on the relay.

...Roger...

Does the relay click ?

fast69cam

Is there any way to test the relay ? The relay is new, along with all of the wiring, new engine harness and a/c harness.