blower control module

[87wishin59]

Hi All,

Anyone know how to test a blower control module for an '87 ?

The blower motor comes on randomly, for short periods of time, while the car is just sitting in the garage. It'll continue until the battery is dead. I disconnected the power to the BCM (by removing the 2 wire plug) for storage over the winter, now I'd like to get this thing figured out.

I took the BCM out, figuring, how much could that part be? My friendly GM Dealer told me $500. They should really let you sit down first before dropping that price on a guy.....

Cheers

 

[SoLow]

When you find out what causes this please let everyone know what you found . My 87 runs on its own as well. Draining the battery is bad :ugh

 

[bradfordsvettes]

this sounds like a bad blower module in the a/c case in the engine compartment area . fairly frequent failure item Steve

 

[jeffyc]

mine went a few months back
i got one at p&g chevy
i think it cost 110 usd
gmparts direct sells them also
part number for mine was 16086891 but thats for a 90-91

 

[87wishin59]

Thanks for the feedback.

I knew $500 was way outta line. Started searching the web and it looks like this is a fairly common problem on all GM cars. I found a couple of interesting threads that this part is common on at least the Buick and Caddy. Also looks like the part may be out of production replaced by Delco 12484912.

I'll spend this week hunting down the part and maybe pay another visit to the local GM dealer when the Saturday help isn't there ......

I'll post the results.

Cheers.

 

[jeffyc]

if that is that part number p&g chevy wants $101.43 for it

this is what gm parts direct got for that part #
12484912
All
MODULE
1
$88.20
$88.20
$88.22
$0.00
$21.17
$109.37


that includes the apox shiping

 

[87wishin59]

Well, went back to the chevy dealer with the new Delco part number 12484912. The <same> parts guy had one in stock, and the plastic part of the unit looks identical to what I have. The "electronic" piece looks different, but I expected that. It's almost the same size, a little smaller (both parts are mostly heat sink). However, there is no cross reference that he could find that states this part works in a corvette. He did verify what I found on the net, that the new part number is for the Buick and Caddy.

Unless someone has a master parts cross reference guide handy, I guess I'll gamble on the part from gmpartsdirect.com. Will post what happens.

The local dealer is Bob McDorman, you'd think that would be the dealer to find out about corvertte issues. They also wanted list price @ $178 for the part. I guess Bob wants me to personally pay for that new corvette showroom of his (it's nice), but I digress ....

Cheers

 

[jeffyc]

the dealer wanted about $300 (canadian) taxes inc to get it out the door
i got mine off the net for about 1/2 that

 

[Agent 86]

Sure sounds like the module. Heres some good reading from the bible
http://members.shaw.ca/dankai/AC%20Electronic.pdf

 

[87wishin59]

Thanks Agent.

I haven't replaced the unit yet. Interestingly, I tried gmpartsdirect.com and they don't have the original part or a replacement part number. Stopped by Autozone, just for the heck of it, they don't show a replacement part either.
Funny how nobody has a reference to this part. Good thing mines' the only one that has ever failed. ;-)

 

[87wishin59]

Hi All,

OK, armed with the little data I could scrape up from the internet, I hit the local junkyard. I found an early 90's Caddy, with the hood lowered which is a plus, and the BCM was the exact same part.
Its located under the hood, against the firewall, under a cover and under some relays. Easy to get to.
Looks like the "upscale" GM cars from the early 90's, or the cars with an advanced climate control in them all share this part, which should include the Buick Park Avenue and the Old 98. There were plenty of LeSabres there, but the BCM didn't match. Since the Caddy part matched, this should mean that the Delco part listed as a substitute should work in the Corvette if you don't want to go to the junkyard.

So, for under $20 I have a replacement module. After replecing the part, it looks the problem is solved. All the climate controls seems to work fine and I don't believe the blower has come on all day. (the battery tender isn't charging the battery, which would be a sure sign).

Thanks to those with comments, and hopefully we've solved the replacement parts mystery!

 

[86-ZZ3]

Would someone be so kind as to tell me where this part is on a '86?

 

[Agent 86]

Left side of evaporator housing.(under hood beside firewall)

 

[86-ZZ3]

Thanks. Was disconnecting all the wrong modules looking for it! Found one off a '93 Caddie Deville at the junkyard. Hope it works (Rockauto says it should be same part).

Addendum:

It works! Just tried a few controls. Original part no. (off an early '86 (build in late '85) was 16047792. Used a 16061602 from the Caddie.

FWIW, the faulty unit (not running when cool) had a resistance of around 700K Ohms. Infinite on the replacement.

 

[86-ZZ3]

Hmm, it's been hot here so I turne don the a/c (or my partner did). Anyway, the blower fan speed, even maxed out, is much slower with this module so I guess it isn't workiong, or not working right.

 

[petesrepairs]

Thanks. Was disconnecting all the wrong modules looking for it! Found one off a '93 Caddie Deville at the junkyard. Hope it works (Rockauto says it should be same part).

Addendum:

It works! Just tried a few controls. Original part no. (off an early '86 (build in late '85) was 16047792. Used a 16061602 from the Caddie.

FWIW, the faulty unit (not running when cool) had a resistance of around 700K Ohms. Infinite on the replacement.

Hi, i've managed to get the module out of the car as i know its on this circuit that is causing the issue off a battery drain, even though the fan never kicks in, but can you tell me how i can test this part with a meter???

 

[86-ZZ3]

Set the multimeter to Ohms and put it across the two contacts of the module.

 

[petesrepairs]

Set the multimeter to Ohms and put it across the two contacts of the module.

This might sound a bit daft, but which 2 contacts? there are 6 in total, of which there are 2 sets of plugs, a 2 pin and a 4 pin plug.

 

[86-ZZ3]

I think it's the 2 pin. It's been some time since I did the work.

 

[boomdriver]

I think its the 2 pin that has the larger red wire and a similar size blk/red wire next to it. I just did this dance last month and forget already...
and, c-4 vettes shared some parts with caddy for several years...not many, but some electronic a/c parts, VATS and a couple other things. Only the top shelf Chevy was allowed to utilize the top shelf GM features off a Caddy.