'91 Park Ave. - Blower Won't Work on HI Speed Setting

[timrice]

Public: Don't know if it's an "official" fire hazard or not, but my rule of thumb is that if you can see or smell smoke, there is some chance that it could catch fire under the right circumstances or conditions. It's definitely not good. I haven't checked Edmunds or Alldata to see if there was any formal GM recall on these--I doubt there was.

As to the $147 cost of the harness, that's a serious gouge, just like with the relay connector that my local Buick dealer wanted $48 for!! I've got to believe you'll do better at a junkyard, or making your own using good wire and the connectors of your choosing.

milltown: Since your blower runs all the time, I would strongly suspect the relay--I'll bet you're on the right track. As to locating it in your car, if it's not on the firewall under the hood like mine was, it may be in the lower right-hand relay panel under the dash--take off the sound insulator plastic on that side and check in that area. Might check your owner's manual, too. Somewhere I'd like to think there's a diagram either in the owner's manual or on the panel itself showing which relays do what. '89 was still back before GM and the other automakers started assuming that nobody would be interested in or capable of doing their own auto repair anymore. They *have* made it harder, that's for sure, but with some determination and forums like this, I've at least learned that many times you can be successful on your own. Another way to locate the relay would be to chase that purple wire back to its source (if you can); I'd guess it attaches to the blower relay.

Clay: Are you still out there? If so, how did your investigation and repair turn out?

[LOWKEY706]

my ac/heat panel was turning off and on just like the first message. i have checked the fuses and realys you guys mentioned and im still not getting any power to that panel. do you think it may be the control panel itself? i also took the dashboard out and checked for bad wires and used a test light to see if any shorts and the test light will light up if the system kicks on but if the system is off, it wont light up. PLEASE HELP WITH THIS PROBLEM. LOOSING IT! THANKS GUYS.

[Clay_Bee]

(91 PA, No Blower Fan)

Hello all,

To update my situation: I finally started to look at the problem on the old Park. I copied the instructions from Tim, Jed and others (Thank You!), purchased a digital multimeter to make my life easier, and have set to work to solve the problem of no blower.

To check the Command Module (this is what I call the external unit in the center of the dash with the HVAC controls): Pulling the dash fascia gives access to the unit. The only pain is getting to the Star screws inside and to the top of the vents. It is a T-15 Star. I used a T-15 driver since a socket will not fit in the vent opening. I found that to keep the screw from falling into the plenum, back the screw out, then flip the vent louver closed on the screw head. You’ll know what I mean if you’ve seen it. Otherwise, I think a magnet on a string will get the screws out of the plenum (I’ll let you know how that goes).

The CCM has a plug with six wires. With the plug pulled from the back of the CCM, and talking about the unplugged wires and plug, there are four wires across the top of the plug (From L-R): Grn, Grn, Blk, Brn. Voltages for the two Grn = 9.0v each, Blk = 0v, BRN 11.79v. On the bottom of the plug, two terminals are used. Grey = 0v, Purple w/stripe = 0v. I assume the Blk wire at 0v is ground.

Next, the CM is connected to the plug: With the HVAC turned off (showing external temperature on the readout). Grey wire = .029v; PurplStr = .004v (I need to measure this again, my notes are tough to read). Pushing the “AUTO” button, the Grey wire changes in this sequence: .029v at OFF to .030v to .031v. I get a click under the right side of the dash. Manually changing the fan speed using the HI LO buttons: .029v at OFF. Pushing LO I get a jump to .031v, then back to .029v. Pushing LO again, I get .030v. Pushing HI for HI Speed Fan, I get .029v. For the PurplStripe wire: Pushing the AUTO button gives a jump to .034, then falls back to .032v. My notes are confused for the other manual settings, but there appears to be a jump to .034v when the manual speed settings change, falling back to .032v.

The fan does not come on for any setting. The HVAC setting for AIR, HEAT and DEFROST cause the plenum doors to operate normally. So those commands are getting to the controller.

Switching to underhood because I want to stand up for a while: The fan itself is new, having been replaced when the problem started. It spins high on battery voltage. There is a fat Blk wire and thinner Purple to the fan plug. At the plug, I have Blk = 0v, Purple = 1.49v! To check for quality of the terminal at the plug, I moved well back on the Purple and Black, entered the wire cover, and found the same volts.

Looking for the relays: On the accumulator side of the firewall there are two Relays in my relay center (plus 4 more on the brake booster side). For the Relays, I measured voltages at the plug itself, then plugged the relay in and slid a probe down to the connector (the plugs have a rubber ‘cover’ on the backside). One relay has 2 Orange wires, a Blk and a Grn. Unplugged, the plug side reads at Oranges = 11.59v both, Blk = 0, Grn = 0. Plugged in: Blk goes to 11, Grn = 0. The other Relay has 2 Purple w/blk stripe at 11.59v; Light Green w/purple stripe at 0v and Dark Green at 0v unplugged on the plug side. The LtGrnw/Str goes to 11.59v plugged in, DkGrn 2v plugged in.

So, this is where it stands. I have 1.49v to the fan. I will stay under hood and look at the resistor module (blower control module as Tim calls it) and check the wires and voltages. I’ll jump it to see if the fan voltage changes. The relays I looked at don’t seem to be the blower relay as explained in previous posts, so I’ll look on the other side of the relay center. I want to make sure of everything under the hood as much as possible before crawling under the dash. If that become necessary, I’m pulling the knee bar out.

I think the dash Control Module is sending signals to a command module under the dash. If anyone knows anything about this, I would appreciate a post. It’s my understanding that GM put one of three possible HVAC control systems in this car, so there is probably some variability in system depending on what options you have.

I’ll post when I make progress. I know little about these electrical components, or electrical in general. Just enough not to short things out. Any advice will be greatly appreciated.

[public]

timrice, thanks for the vote of confidence. I did kinda better. Ended up making my harness end at home. Much beefier than before. This damn car seems to eat electrical connectors under the dash. The high beams did the same thing. These aluminum connectors are junk.

[Clay_Bee]

(91 PA, No Fan)

Well, back under the hood of the Park, I examined the resistor module. It has two plugs. The plug on the right has a large Red wire at 11.82v, and an unused position. Next to that is a 4 terminal plug. The Purple blower fan wire is at 1.62v. There is a Grey w/Blk stripe wire at 7.62v. There is a Blk wire at .01v. The 4th position is empty. Checking the resistance of the unplugged “blower control.” Grey w/Blk stripe is at 1.58 ohms; Purple 87 then 0 ohms (I need to check this again, notes are muddled here). Between the Red and Black terminal, lots of ohms, 87.2.

The purple wire from the resistor module “Y’s” into the blower wire, and it runs into the passenger compartment along with the other wires from the blower and resistor module. Under the dash, I pulled the padded knee bar (10mm socket). While I was there I found that a magnet on a string got the screws I dropped into the plenum when I pulled the fascia. I took various things loose, spent lots of time trying to chase wires, but could not find how the wire runs to the Command Module or where the purple wire comes into the passenger compartment. I tested every fuse with the audible resistance check (how did I ever live without a digital multimeter). The only things I have left to check are the relays on the relay center under the passenger side of the dash.

So far, all of the wires look good, being pliable and not corroded. The only wire problem I see so far is at the blower fan connection (slightly crunchy), but I’m getting good voltage to it when I short it to the battery and it will do until I find the problem. If the relays under the dash are good, I think this old car will get a 4-position rotary fan switch from a Mazda wired to a blower relay in the engine compartment. Clean, simple, never-fail. I don’t smoke, so the switch will look nice in the ashtray.

I need to find what numbers I should get on the resistor module, check the relays under the dash, and the price of Mazda rotary switches.

Tim, your advice about the battery screwdriver is right on! It makes a tedious job less so.

[HotZ28]

[quote=milltown12]I have what seems to be the opposite problem with my 89 PA blower in that it runs all the time.

I assume from reading your post, you have the auto climate control. If the fan runs all the time, you have a bad blower control module. This is a common failure on these cars, (thanks GM)!! You have two different blower motor controls on GM cars. The manual control uses the relay and resistor controls as described above. These have been giving trouble since the 80’s and continue to do so through the 90’s. The auto climate control is a different animal. It uses a resistor module that is set in epoxy and bolted to a heat sink. It is located inside the evaporator box to help keep it cool, however it continues to fail. The default voltage is 12V, straight to the blower motor, un-switched; hence, the blower motor runs all the time. You can pick up one at a salvage yard for 50-75 bucks, however be sure you get the same part number and electrical pins as your existing unit. GM made four or five units that look the same, however have different connections and part numbers. You would think, GM, with all of their resources and brilliant co-op Engineering student designers, that they could design one unit that would cover all applications. I guess they have not conducted a cost benefit analysis on that one yet.
The dealer gets $150.00 for a new unit, and they sell them by the pallet load!

As the owner of several Buicks with ACC (auto climate control) systems, I keep a spare on hand at all times. They will also fail in the open mode, and will have no power to the blower at all!

One other thing I might mention is, an over amp pull from the blower motor is usually what causes failure, so check your full speed blower amperage also. It should be under 20 amps.