1992 LeSabre Heater A/C malfunction

[homeskillit37]

My Mom has 1992 Buick LeSabre Limited. 3.8 V6. The other day she turned the defrost on everything worked no problem. She turned the car off the fan was still going. When she got back to the car the battery was dead. To get the motor to go off we have to unplug the connector from the back of the fan motor. I tried pushing the climate control buttons the lights come on but the fan still blows through the defrost vents on the top of the dash. you can change the temprature from hot and cold but it still wont blow out of any other vents. i tried to take the dash apart to do some troubleshooting but cannot figure out how to get that off either. there must be a lot of hidden screws. Also i know there is a way to reset the computer but cant find it anywhere. i was going to try that to see what would happen. any help would be greatly appriceated
--Stevie

[homeskillit37]

This is what ive found out so far. i figured out how to take the dash out to get to the control panel. I swithced it with the panel from my brothers 1992 Buick LeSabre. didnt do any good. so i put everything back in their respective vehiclas and am at a stand still untill tommarow. The Blower motor is getting 12volts even when the car is off so im thinking a relay somwhere but still searching.

[yogi_123rd]

Sounds like you have two problems here:

1. The blower relay (which sounds like its stuck on) is located on the passenger side engine firewall, under a fiberglass rain guard. The relay you want has wiring that goes to the blower resistor mounted on the engine firewall side of the blower box, and then wiring that goes to the blower motor. Disconnecting that relay will stop the blower from operating.

2. Vent control is actuated by engine vacuum. The supply hose goes to a vacuum accumulator box on the engine firewall near and below the master cylinder. There is a second hose that goes inside the firewall and to your heater unit to which connects to this accumulator box. If the vacuum supply hose is disconnected or the vacuum lines have cracked ends, then the AC/Heater defaults to blow out the defroster.

[homeskillit37]

Thanks for your help i will check those things tommarow nap time got in the way today then work so thats on the todo list tommarow

[homeskillit37]

The vents started working again after that fix. but i removed all 6 of the relays (all out at the same time) in the Fuse and relay box attaced to the firewall on the passanger side and the blower motor is still going. so i am at a loss. wit the relay out there s houldnt be any power. there must be some crossed wires in there somewhere. any other ideas

[yogi_123rd]

I had to consult the Haynes book for a wiring diagram. There's a few more things you can do to isolate it.

Blower speeds: There are two circuits for the blower speed: High speed or low/middle speeds. If it is the high speed circuit that won't stop running, then there is a fuse that can be pulled under the hood in a fuse block (fuse #3 30A). If it is the low/middle speed constantly running, then it is controlled by the AC/Heater.

You may have crossed wires in the connectors. To test, Wiggle the wires with the ignition off.

There are two areas involved. You need a voltmeter for testing. One is a relay and the other is at the blower resistor.

Locate the blower relay with Orange, black, red, Dark blue, and purple wires. Remove the connector and check the lines for voltage: (with ignition off).

The orange wire is a request from the AC/Heater unit for high speed. If it is hot, the AC/Heater unit or the connector has crossed wires - better find and pull the fuse under the hood.
The Dark Blue wire is for low speed control. It too comes from the AC/Hearer unit, but also comes from the blower resistor where the problem could be. The fuse for this circuit is a 25A fuse in the usual interior fuse box.
The black is a ground, the red is always hot, and the purple goes to the blower motor.

Locate the blower resistor: it is located under the hood, to the left of the blower motor in the blower box in the firewall. It will have a connector with a light blue, tan, light blue and dark blue wires. None of the wires here should be hot with the ignition off:
The tan and light blue wires come from the AC/Heater unit.

[homeskillit37]

Thanks for the help yogi. Here is what we found out. It was the Blower Motor Resistor. Which is located behind the Fuse/Relay panel The resister is on the firewall next to the heater core. To get to it you have to remove the the fuse/relay panel by taking off the two nuts that hold it in place. one on each side, the one on the drivers side is undersome plastic and takes an extension to get to. after you remove both nuts you can pull the fuse/relay panel out of the way exposing the resistor. it has two wiring connections going into it. (on our 92 buick) the first one has 1 red wire going into it. the second connection has a purple wire a black wire and a white wire with a black stripe. The resister is held on by the 3 bigger screws. i think like 7 mm. after that it will pull out but it is long so you have to move stuff out of the way just to get it out. after getting the part out its a headache trying to find a new one. the old AC Declo part number wont cross with anything. The only place that could even get one was NAPA and they wanted $170 for a new one and wait a week to get it. we went to the wrecking yard and got one for $5.50. then we found some links where AC Delco has changed their part number
new AC Delco Part #1572530
we were also able to find it as another part number from other stores online as RU-301
here is a link to all of the websites we found and a place to getr a new one for about $100. also there are pictures of what your will be looking for. when installed you will only be able to view just the connectins from the top.

https://www.rockauto.com/dbphp/dbpag...CDelco+Part+Ad

http://www.smpcorp.com/buyersguide/w...partnum=RU-304

https://www.rockauto.com/

[homeskillit37]

here is the part number for the blower motor resistor at napa. Napa BR214

[buickmastermind]

Salvage Yards...What a Life-saver!

[homeskillit37]

An Update on the heater problem. The new resistor blew after a few days. SO we put a another one thinking that one went bad too. That one blew also. The resistor and heat sink were getting real hot real fast. I asked around and got some info. Turned out the blower motor was going bad and pulling too many amps through the resistor causing it to heat up and fail. So I went back to the junk yard to get a blower motor and another resistor. put it in this morning and the resistor and heat sink stay cool. So hopefully now the problem is fixed.