I posted this once before, but didn't get any responses. Someone has to have an idea here, Right?? My A/C doesn't work on 1. 2,3,4,5 work great, but the compressor shuts off when I put it on 1. Living in Florida, you would think this isn't a big deal, but it is bugging me. Any help would be appreciated. Thanks.

 

Casslaw

If you have the manual HVAC head controller, the power for speed 1,2,3,4 to the blower goes through separate resistors to feed the motor the lower voltages for different speeds. On high speed the voltage goes directly to the blower motor. If you have the electronic head controller, the variable voltage speed signal is controlled in the electronic HVAC control head unit. ***But the voltage is reduced in the Blower Motor Control Module. It is located behind the blower module, under the RH side of the instrument panel. This is only true for the 97,98,99. Where it may be located on a newer C5 I don't know. I only have the manual controller in my C5, 97, so I am only farmilar with these years. But that should answer your problem on what controls the blower motor speed and where your problem might be. Judging from the symptoms it sounds like this module because it works on all the other speeds. But please don't hold me to this. Just my two cents. Hope it helps.
Gary

 

Thank You, I have the manual switch in mine, I will try looking for resistors now.

 

Are you getting any codes?
There are very detailed diagnostics in the manual, too detailed to list here. Do you have anyone close by with a set of manuals? Could be the HVAC control unit, the blower motor control module, or the blower motor itself. I wouldn't want to guess from 1000 mi away.

Anyone else?

EDIT: I type so slow you guys got in while I was pecking. Didn't think to ask about manual or auto. glkfam is probably right, the manual system is a little easier, I would lean towards the blower module too.

 

I am not getting any codes at all. I am glad I have the manual unit now.

 

i have the same situation in my 98 c5, i kind of like the slow speed 1 hardly anything comes out at all, but when all you want is a little circulation its great.

however....

just took a road trip to austin, tx for cc, tx. about 3 hours total, my a/c has always been better than i need, we always joke that it must be the suburban a/c put in a vette.

anyways, after about an hour point five, i realized that the a/c wasnt cold and the fan wasnt blowing jack. it was close to 90 that day and i was stuck to my black leather. really pissed. stopped for a break and a smoke, started her up and it was working perfectly. then about an hour later same thing.

now back from road trip havent had a single problem. Is it possible that the lower engine speed at highway cruise has something to do with it? less current or engine speed.

 

Hi, is it the compressor shutting off or the fan. Does it happen with the heat and the ac or just the ac

 

If it is the blower not operating on #1 see below
+++++++++++++++++++++++++++++++++
Blower Motor Low Speed Inoperative Position 1
Blower Motor Is Inoperative At Low Speed (Position 1)<<C60>> Step
Action
Value(s)
Yes
No

DEFINITION: Blower motor will operate at all speeds except Low speed (Position 1).

1
Were you sent here from the HVAC System Check (C60)?
--
Go to Step 2
Go to HVAC System Check

2
Disconnect the HVAC Control Assembly connector C2.
Disconnect the blower motor control module connector C1.
Connect a fused jumper wire between terminal B and terminal H of the HVAC Control Assembly connector C2.
Turn the ignition switch to the ON position.
Connect a DMM between terminal B of the blower motor control module connector C1 and a known good ground.
Measure the available voltage at terminal B of the blower motor control module connector C1.
Is the voltage within the specified range?
10.0 -14.0V
Go to Step 4
Go to Step 3

3
Locate and repair an open or a high resistance in CKT 60.

Is the repair complete?
--
Go to HVAC System Check
--

4
Remove the fused jumper wire.
Connect the HVAC Control Assembly connector C2.
Turn the blower switch to the Low position.
Turn the ignition switch to the ON position.
Connect the DMM between terminal B of the blower motor control module connector C1 and ground.
Measure the available voltage at terminal B of the blower motor control module connector C1.
Is the voltage within the specified range?
10.0 -14.0V
Go to Step 6
Go to Step 5

5
Replace the HVAC Control Assembly. Refer to Control Assembly Replacement .

Is the repair complete?
--
Go to HVAC System Check
--

6
Replace the blower motor control module. Refer to Blower Motor Resistor Replacement .

Is the repair complete?
--
Go to HVAC System Check
--



--------------------------------------------------------------------------------

 

Blower Motor Resistor Replace. Manual AC System
++++++++++++++++++++++++++++++++++
Blower Motor Resistor Replacement
Removal Procedure




Remove the front floor kick-up panel. Refer to Kick-Up Panel Replacement - Front Floor in Interior Trim.
Remove the cover from the I/P electrical center.
Remove the BLO MOT (blower motor) MaxiFuse® #49 from the I/P electrical center.
Remove the I/P lower insulator panel - RH. Refer to Closeout/Insulator Panel Replacement - Instrument Panel (I/P) Lower in Instrument Panel, Gauges and Console.
Disconnect the wiring harness electrical connector from the blower motor resistor.



Disconnect the blower motor resistor electrical connector from the blower motor.



LOOSEN the blower motor resistor forward two retaining screws (nearest the dash mat) approximately 5 mm (0.197 in). (The resistor is slotted at the forward retaining locations.)
Remove the resistor rear retaining screw.
Tilt down the rear of the resistor; use care to not damage the portion of the resistor which fits up into the HVAC module.
Remove the blower motor resistor from the vehicle.
Inspect the condition of the blower motor resistor seal; replace if necessary.
Installation Procedure




Position the blower motor resistor forward retaining slots onto the forward retaining screws and the upper portion of the resistor into the HVAC module.
Align and seat the resistor to the HVAC module.
Install the resistor rear retaining screw and drive until just secure.

Notice
Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.


Tighten all the resistor retaining screws. Tighten
Tighten the blower motor resistor retaining screws to 1.6 N·m (14 lb in).





Connect the blower motor resistor electrical connector to the blower motor.



Connect the wiring harness electrical connector to the blower motor resistor.
Install the I/P lower insulator panel - RH. Refer to Closeout/Insulator Panel Replacement - Instrument Panel (I/P) Lower in Instrument Panel, Gauges and Console.
Install the BLO MOT (blower motor) MaxiFuse® #49 to the I/P electrical center.
Install the cover to the I/P electrical center.
Install the front floor kick-up panel. Refer to Kick-Up Panel Replacement - Front Floor in Interior Trim.

 

WHEW!! My eyes hurt.


That's the detailed info from the manual that I didn't want to post. Thanks bestvettever, you have more patience than me.

 

Hi, no problem, streak. I had the same thing happen when I owned my toyota supra. Couldn't get anything on the lowest speed. Had to take the glove box door and box itself out to reach the module. then it was a 1 minute repair. Once I took out the old broken one and got a look at it, it was no wonder they fail after a while. The wires that create the resistence are very small, and the one used most often,(speed), is the one to get brittle and fracture first. It is not an uncommon repair.
Luck to All.

 

Thanks for the help, I guessed a resistor from the get go, but only having the car for a week or so, I am not familiar with this set up yet. Thanks again