Replacing front blwr. resistor w/relay???/rear AC blower

[Treenail]

In this thread:

http://www.automotiveforums.com/vbul...d.php?t=897292

Old Master shares a tip about replacing the resistor with a relay.

If I go to the parts store and ask for a 40A relay will it be labeled with the same numbers? How do I know which relay to purchase? Is there an application or part number from a supply house?

And...a related question...

The rear AC blower stopped working. I've checked the under dash and underhood fuses, all good. There are some relays under the hood for the AC. How do I test the relays?

Thanks for any help...toasting in Austin...101 today

Tom

[old_master]

The thread you referred to applies only if the front HVAC system High blower speed is inoperative. All other speeds must operate normally on the front HVAC system.

Standard relays all use the same numbers: 85, 86, 30, 87 and 87a. If you're going to Autozone, O'Reilly or Advance Auto Parts, I can give you the correct part number to ask for.

What year is the vehicle?

[Treenail]

OM,

Yes...I understand this replacement is for the front only

I've got a '99 Safari.

Any of the stores....Autozone, O'Reilly or Advance Auto Parts...are close. What is the part number?

Any suggestions on how to test the relays for the rear blower? It's factory I know.

Thanks!

Tom

[old_master]

Here are two 40 amp relays, either one will work, (they might have to order them for you).

Advance Auto parts: http://shop.advanceautoparts.com/web...7CGRP2044_____

Autozone: http://www.autozone.com/autozone/acc...uestid=1238484


As for the rear HVAC, I've looked through the factory wiring schematics and don't see anything with rear being an option. In the passenger side door jamb, there is a sticker with bunch of 3 character codes. These codes are the Regular Production Options, (RPO) and they indicate all options installed on your vehicle when it was bult. Post a picture of the sticker and I'll decode the RPO's and let you know what I find.

[Treenail]

Thanks SOOO much for the numbers. I got the pic first, I'll check on the relay later.

Here is the sticker:

[old_master]

RPO C69 is indeed factory installed rear HVAC ! Only 40,000 of them, pretty rare option.

http://www.compnine.com/vid.php?vin=1GKEL19W0WB534045

I'll have to do some research to find a schematic drawing for it.

[Treenail]

I found that the underhood relays are all the same so I shuffled them around and the rear AC blower still doesn't work.

There are SO many places in the wiring where power can go bad. I'd like a bit of focus or a flow system to start checking power.

Any help is greatly appreciated. triple digit heat is getting to be the norm here in central TX

[old_master]

I'll do the best I can ASAP ! Expecting triple digits here in Michigan on Thursday, if so, it will beat the record high by 10 degrees!

[Treenail]

No rush...the front AC works it just lags a bit with the dark green paint.

[Treenail]

Old Master!

After getting home from the workshop and opening a chilled Shiner Bock I have to thank you sooooooo much for the instructions on replacing the resistor with a relay. My front AC is chillin'! On HIGH!

The relay cost $6 and I had the wire and connectors. After checking the power with my multi-meter I started cutting wires and splicing. The resistor had been replaced so the factory purple wire from the blower motor was red. I found the wiring diagram in my manual and studied it before I tee'd into the red wire.

The wires going into the relay have number tags on them 'just in case'.

With the wiring schematic for the rear AC I think that I can start to follow power from the battery back. I'm kinda thinking that the rear resistor might have blown. If so, I'll probably do the same as the front.

I appreciate your time and effort helping me solve this critical problem. Driving a dark green van without an AC system at 100% is rather uncomfortable. We're in the third week of triple digit highs here in Austin...can I ship anyone some heat? We'll trade for water!

Tom

[old_master]

Thanks Tom, still looking for your schematic. You won't know how to act once that rear A/C gets going!