DEFINITION: The temperature control operates with either too much or too little effort.

Were you sent here from Symptoms or another diagnostic table?

Go to Step 2

Go to Symptoms - HVAC Systems - Manual in HVAC Systems-Manual

Is one of the following a concern of the customer:

Does the temperature control operate too freely?

Go to Step 3

Go to Step 7

1. Idle the engine at normal operating temperature.
2. Cycle the temperature control from the coldest setting to the warmest setting.

Does the temperature change from cold to hot?

Go to Step 17

Go to Step 4

Inspect the connections of the temperature control cable.

Is the temperature control cable disconnected from the temperature door?

Go to Step 15

Go to Step 5

Inspect the temperature control cable and linkage at the temperature door, while operating the temperature controls.

Does the temperature door move while operating the temperature controls?

Go to Step 22

Go to Step 6

Inspect the cable casing while operating the temperature controls.

Does the cable casing move, instead of the cable, while operating the temperature controls?

Go to Step 19

Go to Step 16

Inspect the HVAC control assembly for any debris or obstructions that would increase the effort to operate the temperature controls.

Are there any obstructions?

Go to Step 21

Go to Step 8

1. Disconnect the temperature control cable from the temperature door.
2. Operate the HVAC control assembly with the temperature control cable disconnected.

Does the HVAC control assembly bind now?

Go to Step 10

Go to Step 9

With the temperature control cable disconnected:

1. Manually operate the temperature door.
2. Inspect the door for binding.

Does the temperature door bind with the cable disconnected?

Go to Step 20

Go to Step 10

1. Disconnect the temperature control cable from the HVAC control assembly.
2. Operate the HVAC control assembly with the cable disconnected.

Does the HVAC control assembly bind now?

Go to Step 17

Go to Step 11

With the temperature control cable disconnected at both ends:

1. Extend the cable in both directions.
2. Inspect the cable for binding.

Does the temperature control cable bind?

Go to Step 18

Go to Step 12

1. Inspect the temperature control cable for kinks or bends from incorrect routing.
2. Repair the cable or routing as necessary.

Does the temperature cable still bind?

Go to Step 18

Go to Step 13

Operate the HVAC control assembly with the temperature control cable disconnected.

Does the HVAC control assembly bind now?

Go to Step 17

Go to Step 14

Reassemble the temperature control system.

Is the action complete?

Go to Step 22

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Reconnect the temperature control cable to the temperature door linkage install the cable retainers.

Is the action complete?

Go to Step 22

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Repair the lack of heating or lack of cooling condition. Refer to Diagnostic Starting Point - Heating, Ventilation and Air Conditioning .

Is the action complete?

Go to Step 22

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Replace the HVAC control assembly. Refer to Heater and Air Conditioning Control Replacement in HVAC Systems-Manual.

Is the repair complete?

Go to Step 22

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Replace the temperature control cable. Refer to Temperature Control Cable Replacement in HVAC Systems-Manual.

Is the repair complete?

Go to Step 22

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Secure the temperature control cable casing.

Is the action complete?

Go to Step 22

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Repair the binding door. Refer to Air Temperature Door Replacement .

Is the repair complete?

Go to Step 22

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Remove the debris.

Is the action complete?

Go to Step 22

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Operate the system in order to verify the repair.

Did you find and correct the condition?

System OK

Go to Step 2