There are no codes shown using the DIC to check.

My car is stuck on heat no matter what setting I roll the dials to on my dual HVAC 2000.

I already replaced the vacuum line from the bottom of the canister behind the fender to the back of the intake manifold. The one that controls the directional air flow.

Which vacuum lines or actuators should I be checking with no codes?

What controls the "hot to cold blend"? When I set my car to 60 degrees, 80 degree+ air comes out of both side vents upper and lower.

Thank you,

Donnie

 

Try this and post up what happens, and all codes to include "U" codes and BCM codes.

Re-Calibrating Actuators After Power Loss

Circuit Description
The HVAC Control Assembly receives an actuator position signal from the RH and LH electric actuators. The electric actuator position sensor is a potentiometer that is tied to a 5 volt reference source through CKT 1791 and to ground through CKT 1798, both from the HVAC Control Assembly. The variable output from the potentiometer feeds back a position signal to a pull-up resistor located in the HVAC Control Assembly. This signal is used to determine the necessary drive signal to the electric actuator motor to provide the proper air mix door position. This value is stored in the Keep Alive Memory (KAM) portion of the HVAC Control Assembly.

After replacement of either the LH or RH electric actuator has been completed, reinitialization of the actuators must be performed. Reinitialization can be easily executed by removing the HVAC CON MiniFuse® #27 from the Instrument Panel Electrical Center and then reinstalling the fuse back into its proper position. When the HVAC Control Assembly is first connected to power, the system will perform an initialization routine lasting approximately 60 seconds. During this routine, both RH and LH electric actuators will cycle full travel in both directions learning the end positions. Position feedback readings are sent back to the HVAC Control Assembly and compared to a range of acceptable end readings. If during initialization the position feedback readings are not within the acceptable range, a diagnostic code will be set. If the position feedback readings reach values of 0-5 counts or 250-255 counts, the HVAC Control Assembly will then interpret the reading as a "feedback-short" or "feedback-open" condition respectively. NOTE: Feedback-short or feedback-open conditions can occur due to electric actuators being initialized while not being attached to the HVAC module case

Kevin

 

Kevin,

I'll pull fuse number 27 but I just had the battery disconnected the other day..should be the same right?

and there are NO CODES.

Thank you,

Donnie

 

When the batt is disconnected, all systems are off line PCM BCM etc and all systems come alive when you connect the batt which may cause some "stumbling" in the modules trying to communicate with each other. the car needs to have the batt connected for this task.

Kevin

 

More troubleshooting info..

Air Temperature Control Inoperative Step
Action
Value(s)
Yes
No

DEFINITION: The DRIVER temperature control does not properly control the outlet air temperature.

1
Has the HVAC Diagnostic System Check been performed?
--
Go to Step 2
Go to Diagnostic System Check

2
Install a scan tool.
Turn the ignition ON.
Display the HVAC Data List.
Turn the AUTO button OFF.
Turn the PASSENGER temperature control **** to the center position.
Operate the DRIVER temperature control **** through the full range of adjustment.
Does the scan tool indicate the LH Mix Mtr Position Requested and the RH Mix Mtr Position Requested changing in correct relation to the DRIVER **** position?
--
Go to Step 3
Go to Step 9

3
Using the scan tool Miscellaneous Test attempt to operate the LH Mix Mtr through the full range of adjustment.

Does the scan tool indicate the LH Mix Mtr is operating properly?
--
Go to Step 4
Go to Step 5

4
Using the scan tool Miscellaneous Test attempt to operate the RH Mix Mtr through the full range of adjustment.

Does the scan tool indicate the RH Mix Mtr is operating properly?
--
System OK
Go to Step 6

5
Test and repair the LH Electric Actuator feed and control circuits for an open or high resistance.

Did you find and correct the condition?
--
Go to Step 10
Go to Step 7

6
Test and repair the RH Electric Actuator feed and control circuits for an open or high resistance.

Did you find and correct the condition?
--
Go to Step 10
Go to Step 8

7
Replace the LH Electric Actuator. Refer to Temperature Actuator Replacement .

Is the repair complete?
--
Go to Step 10
--

8
Replace the RH Electric Actuator. Refer to Temperature Actuator Replacement .

Is the repair complete?
--
Go to Step 10
--

9
Replace the HVAC Control Assembly. Refer to Control Assembly Replacement .

Is the repair complete?
--
Go to Step 10
--

10
Clear any DTCs which may have set.
Operate the system in order to verify the repair.
Did you correct the condition?

 

I don't have access to a tech II...

pulled fuse 27..no difference.


Is the "blend" vacuum controlled or electrically?

Thank you,

Donnie

 

I believe the hot/cool is controlled by the temp valves ( basically the flaps on the HVAC) which are controlled by the acutators, thus the acutator problems, but probably not your problem. So, the answer would be electronically. The vacuum from the electronic vacuum selonoid (under the passenger sider) controls where the air comes out, with directions coming from the head unit. I am having the same issuses as you are and have not figured it out yet, but it is cool here at the moment so I need to wait and check when it gets warm as its not a problem when it is cool. I believe my next step after I check again will be Coevette World where they can plug a TechII in and see whats going on. Good luck and let us know if you figure it out. THis is assuming that you have the correct charge, and compressor and everything is working as it should be?

 

I'm almost certain on the charge levels. Same weather here so hadn't been too concerned and hadn't really used the AC.

I'll be getting my own set of gauges on the 5th of April.

In the mean time, I'm going to see if I can test for vacuum on a few of the lines...just gotta track down BC's post with the pics of the AC head/vacuum lines.

DZ

 

There is a vacuum line that goes from the rear of the MAP sensor area which is at the rear center of the intake manifold and runs down behind the battery where it goes through the firewall to the HVAC system. Under the passenger side footwell area, that same line comes through and connects to a vacuum distribution type device. and sorry, but I don't know what it's called. Check for vacuum right there. If none, then you've got a leak which needs to be repaired.

Now my '99 just did the same thing on me a couple of days ago. Lots and lots of heat that I didn't need at the time. I ended up cycling the driver's control down to 60 degrees which forced something to change, most likely the heat/cool blend door which is vacuum controlled, then I started getting cooler air. Set the temp back up to 73 in my case and it was working fine again. It could be the blend door was simply stuck too. The driver's and passenger actuators are electrically controlled and they only direct airflows to the top or bottom as commanded but I don't think they control temperature.

 

I think if you can change where the air comes out, center, defrost, footwell and all is well, you probably are ok on the vacuum. But you might try pulling the fuse in the passenger footwell for the HVAC, and let the actuators re-set, then see what happens. Basically, the vacuum lines control where the air comes out, the acutators control the temp (hot/cold).
I never remember the fuse #, but if its like mine, the fuse cover has all of that infor.

 

This is from Bill Curlee's post:


The vacuum actuators have nothing to do with temperature. The vacuum dampers just control air flow thru various vents:

recirc/vent, floor vents/upper vents/defrost

The HEAT & COOLING are controlled by the ACTUATORS.

Try this:

When you Turn the ignition switch ON, Turn the AC System "OFF"

Clear the HVAC DTCs. When you Clear them, see if you can hear the ACTUATORS CYCLE thru their full ranges. If they do, see if the DTCs stay OFF. Do this several times so that they can calibrate them selves.

Turn the HVAC to ON / AC and see if the DTCs remain OFF. If not, CLEAR the DTCs with the system ON and see if you can hear the actuators cycle.

I did this procedure several times and it fixed my HVAC issues

If this fails to resolve the issue, use a meter and read the fuses for the HVAC head unit to ground and see what voltages you get. The voltage should match actual battery voltage AT the BATTERY. If not, you have a Voltage issue and most likely its being caused by the ignition switch.

The "HOT IN ON" voltage supplied by the ignition switch is very often LOW due to damaged contacts in the switch. Read the voltage AT THE FUSE in the below schematic (Instrument Panel Fuse center, HVAC, Mini Fuse18 )

On the top of each fuse are two small slots. Those are test points. Read that test point to Chassis Ground. It should read the same as voltage take directly off the battery terminals

The ignition switch MUST be ON for this test!