GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1998 🢒 GMC Suburban - 4WD 🢒 HVAC 🢒 Heating, Ventilation and Air Conditioning 🢒 High or Low Temperature Control Effort

Diagnostic Aids

A kinked control cable, a binding valve or a faulty control assembly are possible causes of excessive temperature control rotary knob effort.

Step

Action

Value(s)

Yes

No

1
  1. Check the routing of the cable for a kink, wiring interference or instrument panel interference.
  2. Repair the cable as necessary.

Did you find and correct a condition?

--

Go to Step 2

System OK

2
  1. Disconnect the cable from the temperature valve. Refer to Temperature Control Cable Replacement .
  2. Manually cycle the valve.
  3. Inspect the valve for binding.

Does the valve bind?

--

Go to Step 3

Go to Step 4

3
  1. Inspect the valve seals for proper installation.
  2. Repair the valve seals as necessary.

Did you find and correct a condition?

--

System OK

Go to Step 7

4

Inspect the control for binding.

Does the control bind?

--

Go to Step 5

Go to Step 8

5
  1. Disconnect the cable from the control assembly.
  2. Recheck the control for binding.

Does the control bind?

--

Go to Step 6

Go to Step 9

6

Replace the control.

Is the repair complete?

--

System OK

--

7
  1. Inspect the temperature valve for misalignment of the shaft, a bent shaft or valve, and a warped case.
  2. Repair the temperature valve as necessary.

Is the repair complete?

--

System OK

--

8
  1. Reconnect the cable to the temperature valve.
  2. Reinspect the clearance of the cable around the instrument panel components.

Is the repair complete?

--

System OK

--

9

Replace the cables as necessary.

Is the repair complete?

--

System OK

--