Intermittent A/C Control Panel problem?

Tiny
GORDON2
  • MEMBER
  • 1998 HONDA ACCORD
  • 2.3L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 277,000 MILES
My A/C Control Panel is not always working; the problem is intermittent in my case.

This morning, when using my car's air conditioner while driving, the LED AC control panel lights for inside air flow, re-circulation, and compressor on/off stopped functioning, but at times during the same drive they did work. The problem is intermittent. When the LED lights on the control buttons are not working, the air was not being cooled, but when the lights are working the cooling works (but cooler would be better).

I tried checking things out when I got home. The A/C system worked with the car sitting in a driveway with outside temperature at 79 degrees Fahrenheit. The compressor clutch engages and the radiator fan on the driver’s side comes on when the A/C is turned on. An analog air vent thermometer measured as low as 66 degrees Fahrenheit, about 13 degrees cooler than outside air. I rotated the temperature knob from as cold as possible to as warm as possible, and two minutes later the thermometer was at 118 degrees. I rotated the knob all the way back to the cold side and after a few minutes the AC vent temperature was back at 66 degrees Fahrenheit. The car sat for an hour then I took it for a test drive. The A/C vent temperature is able to get down to about 47 degrees Fahrenheit while driving at 40 to 50 MPH. What I’ve said in this paragraph describes when the system is working.

I also observed the system not working while driving, and initially while it was in the driveway being checked out. When it was not working, the LED AC control panel lights are not lit, the compressor clutch does not come engage and neither of the radiator fans turns on.

When the controls work and the AC is on, the compressor clutch engages and the radiator fan on the driver’s side runs, but the one on the passenger side of the radiator does not run. I am able to turn the compressor on and off and able to control the re-circulation and whether air comes out of the dash vents, floor vents or windshield. When it does not work, I can’t control those items, but the fan speed knob still works.

It almost seems as if I had a bad connection that somehow got better via some use, as the car is driven only once or twice a week.

I have read elsewhere that 1998-2002 Accords have issues like this and that they are caused by actuators below the dash/center console. One actuator is near the gas pedal and seems to control the mode (defrost, dash vent, floor vent) and I think that is called the HVAC Panel Mode Door Actuator 79160-S84-A01. I think the other is called the re-circulation actuator 79350-S84-A01. I’m not sure if I have the correct part numbers or if there are aftermarket parts, but those items are expensive. Some folks seem to be removing the actuators, opening them up, cleaning, reassembling and re-installing those actuators. The indication is that there are electrical contacts inside that get dirty or need to be bent to make better contact. I am not sure about this, but it did seem worth mentioning, hoping to avoid wasting time and money. For now, I will wait until the problem happens again, unless there is another recommendation that might help.
Sunday, May 18th, 2025 AT 1:54 PM

16 Replies

Tiny
KEN L
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The actuators will not cause this problem. To me it sounds like the HVAC control module is going out, I would get a used one on ebay and swap it out. From what you have described the HVAC control module micro processor is out. Here is how to swap it out. Check out the images (below). Please let us know what happens.
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Monday, May 19th, 2025 AT 2:10 PM
Tiny
GORDON2
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Thank you!
From what I can tell, the part is available only as Part # 599-268 Dorman Remanufactured Climate Control Module.

I think the Honda part number is 79600-S84-A01ZA.
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Monday, May 19th, 2025 AT 3:23 PM
Tiny
KEN L
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Ebay is your friend when it comes to parts like this, I have had great luck with anything I have gotten from their website. The only other thing is to check the system grounds which is the black wire to the HVAC module, please use this guide to test it with the module disconnected.

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

Please let us know what happens.
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Tuesday, May 20th, 2025 AT 8:49 AM
Tiny
GORDON2
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I bought a “made I China” replacement part from Amazon that was priced close to what I saw on eBay but did not require a $200 core. It does seem to be working. It actually felt cooler than before, which surprises me. With an outdoor temperature of 84 degrees Fahrenheit I got a temperature of 44 degrees from the vent, and it may have been cooler when driving. The buttons on the panel work, the compressor clutch operates and the radiator fan works as it did before.

Thank you for all the help!

Beyond that, I made a few mistakes that some might avoid or just get a chance to laugh at my mistakes.

Before reinstalling the clock, I took it for a test drive. The blinkers did not work, evidently those tie in because the emergency flasher on/off button is in the same little frame/panel (which I later cracked when reinstalling, so it now has some electrical tape on it) as the clock.

When I first tried reinstalling the clock, the emergency blinkers came on right away, and the push button on/off switch would not pop out. It turns out that when removing I had disconnected the wire at the wrong location, as there is the switch, the cable connection from the car, and a middle part. The middle part actually should have stayed with the switch. Even worse, I guessed that I had dropped a spring that goes between the on/off button and that middle part which is why the button would not pop out.

I removed the radio and fished around behind all that with a magnet on a stick. The magnet found the spring and it all went back together, which is when I broke some of the plastic on the clock frame/panel. Ugh. Oh well, it’s all working for now. I wonder if I could find the replacement frame/panel for the clock and hazard light on/off button.
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Thursday, June 5th, 2025 AT 2:53 PM
Tiny
GORDON2
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Tried to update one of the pictures on prior post, but could not get the old one to delete.
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Thursday, June 5th, 2025 AT 3:06 PM
Tiny
KEN L
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I am glad you got it working, thanks for letting us know, we are here to help, please use 2CarPros anytime.
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Friday, June 6th, 2025 AT 12:36 PM
Tiny
GORDON2
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Could something go wrong if the system is too cold?

The AC is definitely running much cooler, and while I like the cold air, I wonder why it is so different and whether this is normal. Could something go wrong if the system is too cold? Could I have too much pressure in the system? It got down to about 23 degrees Fahrenheit on a 5-mile drive with it being 80 degrees and partly cloudy outside.
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Saturday, June 7th, 2025 AT 6:53 AM
Tiny
KEN L
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Hmm, usual this will be a temperature sensor on the evaporator core, but can I ask what the high side pressure is while the system is running?
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Saturday, June 7th, 2025 AT 9:26 AM
Tiny
GORDON2
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I do not have a gauge tool for measuring the pressure, unless OBD II would tell me.
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Saturday, June 7th, 2025 AT 9:42 AM
Tiny
GORDON2
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Thanks for all the help.

Is the temperature sensor on the evaporator core this part? 80560-SV4-A41?

https://www.amazon.com/Honda-Accord-80560-SV4-A41-Temperature-Sensor/dp/B0161ONCR6

If I am going to check the pressure, which tool makes the most sense to buy?
Lowes has a VEVOR 4 Way Ac Manifold Set for under $50, so I might get that.

There is also a Pittsburgh one at Harbor Freight for about $65, but the one from Lowes seems to have a few more pieces. Both come in what looks like exactly the same plastic box.

But if I might need a vacuum pump (seems unlikely for this problem, but) maybe I should consider something from Amazon such as a VEVOR 4 CFM Vacuum Pump and Gauge for about $150, but then there are choices regarding which gases are supported. My car uses R134a. Is there one tool that handles all types of refrigerant gasses? I'd rather get a tool that can handle whatever is being uses these days. Is an R32 "explosion proof" compatible tool set also compatible with R134a. How about this?
https://www.amazon.com/VEVOR-Refrigerant-Manifold-Detector-Applicable/dp/B0C64NG5QY/ref=sr_1_2_sspa?crid=28GEFPGEC5GRP&dib=eyJ2IjoiMSJ9.4XQrrgSsz5uqbRqspw-PC72a7XTwgSIUrmoQzRPPKox9OBnsXwG3eoieI7Jbh9g4wbII0gdjYl1mB_f16Lz3ccMzPmpfqUz6ryhqMjMxkPQ.zJyeLZzdLlfvXAGa8myAtim4NiR-Fhcdb_ksP5hS2y0&dib_tag=se&keywords=VEVOR%2B1%2F4-HP%2B110%2B-Volt%2Bvacuum%2Bpump&qid=1749404219&sprefix=vevor%2B1%2F4-hp%2B110%2B-volt%2Bvacuum%2Bpump%2Caps%2C155&sr=8-2-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&th=1
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Sunday, June 8th, 2025 AT 11:08 AM
Tiny
KEN L
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OBD will not tell you. Yep, I would get this one which will do 134a. They don't make sets that do both 134a and 1234yf so you will need to decide which one you want to service. The 1234yf is for newer cars and it is flammable.

https://amzn.to/4dRRzl3

Please let us know what happens.
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Sunday, June 8th, 2025 AT 11:30 AM
Tiny
GORDON2
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Thanks Ken. I appreciate your help, as I clearly have not been down this path before.

I spent more time than I'd like to admit trying to remove the lower part of plastic case for the evaporator. For today it is a failure, but I was at least able to see the temperature sensor on the evaporator core, part 80560-SV4-A41. To do that, I had to hold the case pried open with the handle of a screwdriver to take a picture. I don't have enough space to reach it to remove and replace. It seems as though there is something in the rear of the lower part of the evaporator case that is preventing me from removing it. I'll post a picture, but better put the car back together for now, before I forget where things go.
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Sunday, June 8th, 2025 AT 3:51 PM
Tiny
GORDON2
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Given that I was not able to fully access the temperature sensor on the evaporator core, I decided to try the original HVAC control module, the one with the intermittent failures. I test drove it to the same location as I did with the part from Amazon, but with the original control module, the vent temperature only got down to about 43 degrees Fahrenheit. If the temperature sensor on the evaporator core was the problem, I’d expect the same problem with to occur with either HVAC control module, but that is not the case.

I think my temperature sensor on the evaporator core is ok, and I returned the HVAC control module to Amazon (actually to the place the shipping label provided via Amazon). I think I will try eBay and perhaps I will have better luck with a rebuilt part.
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Monday, June 9th, 2025 AT 8:35 AM
Tiny
KEN L
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Most of the time the evaporator will need to be removed before the temperature sensor needs to be replaced. This is why I wanted to get the pressure readings first. If the system is a little low it will freeze up the evaporator core due to low, low side readings. Please check out this guide:

https://www.2carpros.com/articles/why-your-cars-ac-evaporator-ices-up-and-how-to-fix-it

Please go over this guide and get back to us.
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Monday, June 9th, 2025 AT 8:52 AM
Tiny
GORDON2
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The refurbished HVAC control module from eBay seems to work well. It functions as expected, and did not fail on the first test drive, but I will give it a second test on another day. The temperature never got below 40 degrees Fahrenheit and was typically operating around 42 to 44 degrees; rather much like the original part that otherwise had the intermittent failures. The refurbished HVAC control module from eBay does observably control a duty cycle that turns the compressor (and one radiator fan) on/off periodically while maintaining a steady temperature. It also controls the dash vent vs. Floor vent vs. Windshield vent, as well as the valve for heat and the power for the rear window defroster appears to come on, but I did not have any frost to prove that was actually working.

Since the temperature is no longer outrageously low as it was with the Amazon/made-in-China new part, the symptoms described in the guide are no longer present. I don’t see much of a chance of making ice in the evaporator core at the temperature range observed with the refurbished part from eBay.

I think this problem is solved. Another test drive tomorrow will be done anyway.

Thanks for all the help!
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Sunday, June 15th, 2025 AT 9:04 AM
Tiny
KEN L
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Yay! I have had good luck with ebay parts, not so much with cheaper alternatives. Glad you could get it fixed, thanks for letting us know. Please use 2CarPros anytime we are here to help.
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Sunday, June 15th, 2025 AT 10:27 AM

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