FNFastZ06

I'm having continuing HVAC Blower issues. Replaced Module & Blower Motor. All worked fine for 3 months. Had 4 days of rain, Humidity was high in car, but mildly damp carpet, no condensation on glass or instruments.

Started up put on A/C and set blower to high. Roll down driveway backwards and a waterfall of water comes from behind the dash on to pass. side floor. 2 minutes later, blower stops. Get back home and start to work on it

Fusebox and computer in kick area was bone dry. Disconnected battery, removed carpet, dried everything with fans in an A/C garage set to COLD.

Removed and inspected all 4 udders and HVAC drain tube. All were dry and without foreign material. Check all fuses and OK. Pulled blower motor and module. Area inside plenum was bone dry motor has some signs of surface rust but bench tests good. Module looks pristine, opened and no signs of corrosion on the circuitry. Bench tests good too.

Reassemble and hook up, no blower. A/C compressor kicks on and engine cooling fans come on properly.

The PS sill was quite wet so this leads me to leaky door, window or windshield gaskets which I'll address tonight. I'm thinking ground connector F202 is corroded and not completing the circuit.

So question is, how do you access the ground bolt shown in this photo I borrowed from Bill Curlee? Can't get a wrench on it or a universal socket.
Or can it be disassembled while still bolted down?

jim993

I thought the passenger side was the easier of the two sides to get out. I used a small box end wrench, 1/12 turn at a time. You might have to grind the wrench (last resort, grind the car) to get the 1/12 turn.

Getting the driver side bolt started was the hardest for me. One pinky for guidance, 1/12 turn and it started.

I use dialectric grease on everything, like I have been doing on automotive electrical connections for the last 15 years. Once they are clean and greased, no more corrosion or connection problem.

The connection pack can be dissassembled, but I don't think in place because the back tab is inaccessable in place.

FNFastZ06

I can get it about a 1/4 turn, but the whole assembly turns together, even if I hold the connector with my other hand. I totally concur with dielectric grease, I use it on all the connections I R&R.

But here's a twist, It's not the ground (I don't think anyway). While I'm down here doing these circus freak contortions, I decided to run a jumper from the ground bolt to the blower case. Fan runs, 1 speed only. I think this is telling me the module is not good?

jim993

I don't know about the module. Only one speed implies that as one cause.

If the ground pack is moving around, I think you need to get the bolt out and make sure the ground is good though.

FNFastZ06

Just got it done. Went and got a offset box end at Autozone. Ground a notch in it and it only took 20 mins of miniscule turns.

Connector looked good, but I sanded the male contacts and lug lightly anyway. Sprayed with Boeshield and reassembled. Cleaned the bolt and tapped hole with thread chaser and sprayed with Boeshield. Reinstalled and still nothing. Called the vendor I purchased the module from 3 months ago and he's shipping me a new one tomorrow, no questions asked.

jim993

Good luck.

Save that wrench for the driver's side. There are two ground packs there, the upper one has a wire going to the bolt through the tab on the lower one. I remember even less room there.

FNFastZ06

!!!*$$%#

Just put in brand new module and no joy.

So, to recap... '03Z, fuses all good. Removed, tested with meter and checked contacts, applied Boeshield. reinstalled and made sure seated positvely. Check with meter and 12v going through all.

Replace module with 2nd new one (from GM), blower still no workie. Works full blast when ground case to chasis.

Disassemble G202 and SP202. Look clean. Lightly sand contacts and clean threads. Spry with Boeshield. Still nothing.

Any new suggestions?

lucky131969

I certainly hope you are not using Boeshield T-9

FNFastZ06

I use it like any dielectric. After the connection is made, to prevent corrosion and and keep moisture out.

lucky131969

I see no mention if you have manual or auto a/c.

FNFastZ06

Sorry it was in the earlier thread. Dual zone auto.

lucky131969

Based on the schematic, what voltage/ground checks have you performed.

FNFastZ06

Since I'm not good with elec schematics, I've pulled and checked all related fuses... 51, 27, 18 in Pass footwell, 34, 24 in engine compartment. Verified 12v though them. Pulled SP202 at G202 inspected and cleaned, replaced. all other circuits running through that ground pack function properly. There is 12v coming from module pin out, grounded blower case, runs full blast.

FNFastZ06

BTW, blower is 3 mo. old. From GM

lucky131969

At the blower motor control processor(BMCP), you should have the following:

Pin B - Battery (red wire) - you grounded the case, so that suggests this is good
Pin C - Variable output from the control module for blower speed (tan wire)
Pin A - Ground (black wire)

Do you have a good ground at Pin A?
When backprobing Pin C , does the voltage vary as you change the blower speed on the control panel?

FNFastZ06

Pins B & A = 12v

Pins A & C = .001v at low, .003v at hi

lucky131969

....and the resistance to ground on pin A?

FNFastZ06

.001

lucky131969

Hmmm....that's not good.

I had to dig on my hard drive, because I know that I had taken pics last time I troubleshot this for someone.

Back probing the connector can be a challenge, so I always remove the contact seals to ensure I get the jumper wires wedged in snug.

Pics top to bottom:

1) Connector seals pulled back

2) Jumper wires in place. Even though I'm only testing the tan wire for the blower control circuit, I always use an additional jumper for the battery feed, so I can double check I have a good ground, ,meter connections, etc. Tested with connector plugged into the BMCP.

3) Meter reading with blower at full (high speed) : 1.146 VDC

4) Meter reading with blower at mid way (medium speed) : 3.465 VDC

5) Meter reading with blower off (lowest setting) : 4.636 VDC

FNFastZ06

That's a lot of good info right there, thanks! I'll be back after I check it out.