Error Code P0646: What It Means & What To Do?
![Discover Error Code P0646: What It Means & What To Do? For Your Vehicle Discover Error Code P0646: What It Means & What To Do? For Your Vehicle](/cms/p0646-obd-ii-trouble-code-ac-clutch-relay-control-circuit-low-ac-compressor-clutch-harness/images/p0646-obd-ii-trouble-code-ac-clutch-relay-control-circuit-low-ac-compressor-clutch-harness-desktop.jpg)
![Discover Error Code P0646: What It Means & What To Do? For Your Vehicle Discover Error Code P0646: What It Means & What To Do? For Your Vehicle](/cms/p0646-obd-ii-trouble-code-ac-clutch-relay-control-circuit-low-ac-compressor-clutch-harness/images/p0646-obd-ii-trouble-code-ac-clutch-relay-control-circuit-low-ac-compressor-clutch-harness-desktop.jpg)
OBD Code P0646 - A/C Clutch Relay Control Circuit Low
Diagnostic trouble code P0646 is technically
described as A/C Clutch Relay Control Circuit Low. This code indicates that a
fault has been detected in the A/C clutch relay control circuit. The code is due to a defective A/C compressor control relay, or an A/C
compressor driver in the PCM. Code P0646 is set by the PCM
when it detects a low voltage situation within the air conditioning relay
control circuit.
Learn More About OBD Error Code P0646
P0646 is a diagnostic trouble code (DTC) for
"A/C Clutch Relay Control Circuit Low". This code appears when PCM or
other supporting control modules has registered a fault in the A/C clutch relay
control circuit. This is a generic diagnostic trouble code (DTC) and applies to
many OBD-II vehicles. Trouble code P0646 is associated with the air
conditioning (A/C) clutch relay control circuit. The purpose of the A/C clutch
relay control circuit is to control the operation of the air conditioning. This
is accomplished by providing power to the A/C clutch to engage the A/C
compressor.
When the PCM or one of the other supporting
control modules has detected improper signals within the A/C clutch relay
control electrical circuit, code P0646 will be set.
What causes this problem with the A/C Clutch Relay Control
Circuit Low?
- Flawed A/C compressor control relay
- Inoperative A/C Clutch
- Faulty or defective wiring
- Loose or corroded connector
- Broken control module ground strap
- Blown fuses
- Fallacious PCM
Replace/Repair These Parts To Fix OBD Code P0646
- A/C Clutch Relay - The AC
compressor relay is responsible for supplying power to the AC compressor and
clutch. Without this relay, the AC compressor will not have power and the AC
system will not function. Replace or repair it if you discover it faulty.
- A/C Compressor Clutch - At the heart
of the air conditioning unit of a car is the compressor that pressurizes the
refrigerant and pumps it through the A/C system. It derives its power directly
from the engine flywheel and, in a similar way to the drive chain of the car, a
clutch controls its operation. It should be inspected thoroughly and repaired
as required.
- A/C Compressor - The compressor
is the power unit of the air-conditioning
system that puts the refrigerant under high pressure before it pumps it into
the condenser, where it changes from a gas to a liquid. Check it out thoroughly
and if you find it faulty replace it.
Symptoms Of OBD Error Code P0646
Common symptoms of this code are:
- Inoperative A/C system
- Malfunctioned A/C
- Illuminated check engine light
If the code is stored but the check
engine light is not illuminated, the code may show up as “pending”.
How To Correct P0646 A/C Clutch Relay Control Circuit Low
If you can drive without the comfort
of A/C then you can fix this code as per your convenience but keeping any
trouble code for long time is not good as it may lead to some other issues
aswell. It is always advised to diagnose and fix this code by an experienced
technician as this circuit can be very complex and include several relays,
fuse-able links and fuses in some circumstances. To fix this code following
repairs or replacements may help:
- Replacing the A/C clutch relay
- Replacing blown fuse or fuse-able
link (if applicable)
- Cleaning corrosion from connectors
- Repairing or replacing wiring
- Repairing or replacing ground straps
- Replacing a control module
- Replacing the A/C clutch
- Replacing the A/C Compressor
- Flashing or replacing PCM
Check out our web Parts Avatar
Canada for all the parts you require to fix any trouble code. You will find all
the best options available there that too at best prices.
Easy Diagnosis Of Engine Error OBD Code P0646
The step by step analysis and
diagnosis is recommended by a qualified technician using high grade diagnostic
tools to check for all the problems and solving them. One should follow the
below mentioned steps to diagnose this trouble code:
- Visually inspect all wiring and
connectors. Repair or replace all the damaged, disconnected, shorted or
corroded wiring, connectors or components.
- If wiring, connectors and all other
components are working fine, connect the scanner to the diagnostic port and
record all stored codes, and freeze frame data. Clear codes and test drive the
vehicle to see if the code returns.
- If the code doesn’t immediately
return, there could be an intermittent condition. Intermittent conditions are
tough to diagnose and may need to be allowed to return and worsen in order to
get an accurate diagnosis.
- Check out if any engine or
transmission ground straps, cables or wires that were left loose after repairs
were performed.
- Use the digital volt/ohmmeter to check continuity between individual connectors. Compare your findings with manufacturer’s specs and repair any open/shorted circuits as required.
Common Mistakes When Diagnosing the P0646 Code
The most common mistake in
addressing this code is replacing the A/C components when the fault is simply
in the wiring, ground straps, or other components.