A/C stopped working

Hi w_noel_smith, You can perform simple checks to understand what could possibly be wrong. When A/C is turned on, check if the cooling fans are working and the compressor is engaged. How to Retrieve a Diagnostic Trouble Codes The Heater Control Panel has a self-diagnosis function. To run the self-diagnosis function, do the following: 1. Turn the ignition switch OFF. 2. Turn the fan switch OFF, the temperature control dial on Max Cool and the mode control dial on Vent. 3. Turn the ignition switch ON (II), then press and hold the recirculation control switch. Within 10 seconds while holding the switch down, press the rear window defogger switch five times. The recirculation indicator blinks two times, then the self-diagnosis will begin. If there is any problem in the system after self-diagnosis is finished, the recirculation indicator will blink the Diagnostic Trouble Code (DTC) 7 through 13. When problems in the evaporator temperature sensor circuit are detected (codes 14 and 15), the A/C indicator will blink the DTC. If no DTC's are found, the indicator will not blink.

Canceling the Self-diagnosis Function 4. Turn the ignition switch OFF to cancel the self-diagnosis function. After completing repair work, run the self-diagnosis function again to make sure that there are no other malfunctions. Max Cool Position Function 5. When the mode control dial is in the MAX A/C position, the heater control panel will automatically select the Recirculation mode and turn the A/C on. The recirculation switch and A/C switch are disabled and cannot be turned off in this mode. If the control panel fails to function as described, replace it.

KHLow2008 - Thanks for the very detailed instructions. I had a different problem with the A/C and was able to get a DTC code (12) using your instructions, but I do not know how to interpret it now. Where can I find this information?

DTC 12: A Problem in the Blower Motor Circuit

1. Check the No. 12 (40A) fuse in the under-hood fuse/relay box, and the No. 14 (10A) fuse in the under-dash fuse/relay box.

Are the fuses okay?

Yes - Go to step 2.
No - Replace the fuse(s), and recheck.

2. Connect the No. 2 terminal of the blower motor 2P connector to body ground with a jumper wire.

3. Turn the ignition switch ON (II).
Does the blower motor run?

YES - Go to step 4.
NO - Go to step 17 .

4. Turn the ignition switch OFF.

5. Disconnect the jumper wire.

6. Disconnect the power transistor 4P connector.

7. Check for continuity between the No. 2 terminal of the power transistor 4P connector and body ground.

Is there continuity?

YES - Go to step 8.
NO - Check for an open in the wire between the power transistor and body ground. If the wire is OK, check for poor ground at G501.

8. Connect the No. 2 and No. 4 terminals of the power transistor 4P connector with a jumper wire.

9. Turn the ignition switch ON (II).
Does the blower motor run at high speed?

YES - Go to step 10.
NO - Repair open in the wire between the power transistor and the blower motor.

10. Turn the ignition switch OFF.

11. Disconnect the jumper wire.

12. Disconnect the heater control panel 30P connector.

13. Check for continuity between the No. 16 and No. 17 terminals of the heater control panel 30P connector and body ground individually.

Is there continuity?

YES - Repair any short to body ground in the wire(s) between the heater control panel and the power transistor.
NO - Go to step 14.

14. Check the continuity between the following terminals of the heater control panel 30P connector and the power transistor 4P connector.

14.

Is there continuity?

YES - Go to step 15.
NO - Repair any open in the wire(s) between the heater control panel and the power transistor.

15. Reconnect the heater control panel 30P connector.

16. Test the power transistor (see Power Transistor Test ).

Is the power transistor OK ?

YES - Check for loose wires or poor connections at the heater control panel 30P connector and at the power transistor 4P connector. If the connections are good, substitute a known-good heater control panel, and recheck. If the symptom/indication goes away, replace the original heater control panel.

NO - Replace the power transistor.

17. Disconnect the jumper wire.

18. Disconnect the blower motor 2P connector.

19. Measure the voltage between the No. 1 terminal of the blower motor 2P connector and body ground.

Is there battery voltage?

YES - Replace the blower motor.
NO - Go to step 20.

20. Turn the ignition switch OFF.

21. Remove the blower motor relay from the under-hood fuse/relay box, and test it (see RELAYS ).

Is the relay OK?

YES - Go to step 22.
NO - Replace the blower motor relay.

22. Measure the voltage between the No. 3 terminal of the blower motor relay 4P socket and body ground.

Is there battery voltage?

YES - Go to step 23.
NO - Replace the under-hood fuse/relay box.

23. Turn the ignition switch ON (II).

24. Measure the voltage between the No. 2 terminal of the blower motor relay 4P socket and body ground.

Is there battery voltage?

YES - Go to step 25.
NO - Repair open in the wire between the No. 14 fuse in the under-dash fuse/relay box and the blower motor relay.

25. Turn the ignition switch OFF.

26. Check for continuity between the No. 1 terminal of the blower motor relay 4P socket and body ground.
Is there continuity?

YES - Repair open in the BLU/WHT wire between the blower motor relay and the blower motor.
NO - Check for an open in the wire between the blower motor relay and body ground.
If the wire is OK, check for poor ground at G301.

Can you provide a list of DTC meanings? I am getting DTC 9.

When I turn my air conditioning on it is not blowing cold air. There appears to be no leak under my hood. My blowers work fine. What could be the problem?

Hi Tredick,

It sounds like the system is low on Freon but to be sure lets go over this guide.

https://www.2carpros.com/articles/car-air-conditioner-not-working-or-is-weak

Please run down this guide and report back.

Cheers

Compressor froze up. Independent shop replaced compressor, condenser, and expansion valve with new aftermarket brand. He flushed all lines and evaporator.
charged system and not cool and high pressure is way too high about 400, kicks compressor out. low side okay. He then replaced expansion valve again and again took everything off and flushed and put new desiccant bag in dryer, he found no foreign materials. Recharged and same high side way to high and not cooling. Any help would be appreciated.

Hi Texsman,

What was the low pressure reading?

Possible causes.

1. Excessive refrigerant.
2. Insufficient condenser cooling.
3. Air in system.
4. Faulty expansion valve or heat sensing tube not installed correctly.
5. Restricted lines, check hoses for internal collapsing.

The original problem was just that the blower fan did not work, so I took it to a local garage. Who told me I needed a replacement fan speed controller board. I did not believe them so I investigated the problem myself. I eventually got the fan working intermittently but the fan speed controller does not have any control over the fan speed even if switched off. Nor do any of the lights illuminate on the control knobs when selected. I have checked all the fuses in the fuse box and all are good. Any ideas anybody?

Hi mickys27,

Looks like the control panel is faulty. Internal circuit is missing some power supply. A replacement panel is necessary.

A/C is cold only when driving. Stops cooling as soon as I stop at a light or stop sign, at the light or when stopped it draws power from engine when the compressor turns on. I am mechanically inclined but A/C is really not my strongest area.

Does the engine run hot if it sits and idles? If not sounds like your AC condenser fan is not working.

Engine was running hot before so I changed the thermostat. Perhaps it was not even the thermostat? It has overheated a couple of time since. It was a challenge to change that thing because it was underneath the manifold. I checked the fan before, it was working, I will double check it. Thanks for the reply.

You are welcome if the thermostat is good I would be looking at the fan especially with AC shutting off and engine overheating.

We had a check engine light on which happened to be some kind of manifold issue which was fixed.

However, before that and still now, when its warm here in Texas (around 80+) and my wife has the AC is on, it feels like the car will shut off. It kicks down and then comes back but has never shut off that I know of.

I went to AutoZone yesterday. I did not check the error code since the Check Engine light is not on; however I did have the alternator checked and it was giving out normal Watts/Amps.

Any suggestions on what is causing this?

Hi HondaOwnerTX,

If the idling system is not working correctly, the compressor cutting in would result in the idling speed dropping. When this occurs, the engine would seem like it is stalling but it would then increase and stabilise again.

Get the IAC and throttle body cleaned and retest.

Hey KHLow2008,

Thanks for the quick response. I gather to get this done, I need to take it to a qualified mechanic, correct? Do you have a median range of what this might cost?

Thanks,
Charles

Actually this is a rather simple job and if you are a DIY guy, it is possible to get it done yourself.

Get a can of carburetor cleaner and a piece of rag.

Remove the air cleaner hose and spry some carburetor cleaner into the throttle body. Spray some into the ports inside the throttle body and let it soak for a while.

Meanwhile use the rag to scrub against the inside of the throttle body, opening the throttle plate manually and get the area where the throttle plate seats at closed position clean.

Starting might be difficult due to the presence of the carb cleaner.

Blower motor not working.
I read your sheet but you have not stated where the 4P connector is or the G501 and G301. The sheet is very clear on all counts but locations of connectors and body grounds. This is a friends daughter car they do not have much money she just finished school to become a teacher. Please help.

Did you test the blower motor?

Hey KLOW2008,
I am having the same problem as TUYHAYES (ran diagnostic and system is stating DTC 12)
I have check the fuses and the blower motor but confused by the next steps (6-8) what are your referring to? Power transistor 4P connector and the No. 2 and No. 4 terminals? Locations? Thanks!

Hello,

Is the blower motor working? Here is a guide to help test and see what's going with the blower motor wiring diagrams so you can see how the system works:

https://www.2carpros.com/articles/blower-fan-motor-works-on-high-speed-only

Check out the diagrams (below). Please let us know what you find.

Hello ken,

Yes I have tested the blower motor and it comes on just fine. My system is throwing a DTC 12 according to the self diagnostic I ran on the system. I have checked the fuses and again have tested the blower motor.

My original problem is my fan will not come one no matter what setting it was on. It was working intermittently and we noticed a relation of if we left the fan on and shut the vehicle off (fan control set on any speed) and it would not work after that. If we left the fan off and shut of the car (Fan control set to off) it would turn right on. In instances of when the fan stopped working because we had left it on, it would be months before it would start working again but once it did, and we left the fan off when shutting off the car, all was good.

Hello,

It sounds like the blower motor transistor has gone out. Here are diagrams to help you see the location and how to change it out. Check out the diagrams (Below). Please let us know what happens.

Yes, that part actually was the first part I replaced before I ran the diagnosis. it ran for a little while after I installed it but after about three days it just stopped working again. S short somewhere? I need to test the old transistor and see if it’s fine. Will try to do that tonight.

It can be the controller as well but lets check the wiring. here is a guide to help you see how:

https://www.2carpros.com/articles/how-to-check-wiring

Use the wiring diagrams from the post above.

I tested the relay coming off the transistor for the blower motor.
Out of 4 I got power off of 2. The blue/red I am getting .5 volts, and I am getting .02 off the blue/yellow. The battery in the car was dead when I got too it so I started charging it before I tested. Do I need to try again once the system is charged?

Yep, it sounds like the resistor is bad. did you try a new one?

If you mean the blower motor transistor, then yes I have. Forgive me if I was not correct in my description. I tested the relay that plugs into the blower motor transistor. But you said resistor. that’s a different part right?

No it is the same thing. We are missing something here. Can you go back over the wiring diagrams to see where you are losing power start at the fuses? Also use the guide above to check the grounds.