U0164

Lost Communication With HVAC Control Module

Car Fault Codes Network

Can you still drive? Yes, normally

Who can fix it? Needs a workshop

Typical repair time 30 minutes – 4 hours

Typical cost SAR 100 to 3,000

What it means

The HVAC control module runs cooling, heating, blower speed and air distribution, and on many vehicles sends the A/C compressor request to other modules. This code sets when its messages stop reaching the network. The A/C may stop or behave oddly, and symptoms depend on how the system is wired on each vehicle.

Symptoms5

No cooling, or the A/C compressor does not engage.
A/C control panel not responding or its display blank.
Cabin blower stuck on one speed or not working.
Air direction or temperature does not change.
Difficulty clearing fog from the windshield in humid weather.

Possible causes6

Blown HVAC module power fuse.
Weak battery or low voltage.
Loose or corroded module connector behind the dash, sometimes from A/C condensate leaking.
Poor ground connection.
Open or shorted network wiring to the module.
Internal HVAC module failure.

How to diagnose5

Check the battery and the HVAC module fuse.
Try to connect to the HVAC module with a scan tool; if it does not respond, measure power and ground at its connector.
Inspect the connector for looseness or corrosion, and check the passenger floor for water from the A/C drain.
Check the network lines to the module and compare their resistance with the manufacturer specification.
Make sure an aftermarket radio or screen installation has not disturbed the network wiring in the dash.

How to fix5

Replace the blown fuse and charge or replace the battery.
Clean the module connector, repair the ground and clear the A/C drain if it is blocked.
Repair damaged network wiring.
Replace the HVAC module if proven faulty, then program it and calibrate the air doors if the manufacturer requires it.
Clear the codes and test cooling, blower speeds and air distribution.

Repair cost

0–500

500–2,000

2,000–5,000

5,000+

In Saudi riyals; the highlighted part is the expected range for this fault.

The cost is low for a fuse or connector, and rises when the HVAC module or control panel must be replaced and programmed.

Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026

Frequently asked questions

Is my A/C low on refrigerant because of this code?

No. This code is about the control module's network link, not a refrigerant leak. Do not recharge the system before fixing the communication and checking system pressure.

Can I drive without A/C?

Yes, it does not affect the engine or brakes, but in extreme heat it can tire the driver and make defogging hard, so fix it soon.

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This guide is for information only and does not replace an inspection by a qualified technician. If the fault involves brakes, steering, engine temperature, electrics or refrigerant, do not attempt the repair yourself.

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