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Aircon Issue - Pressure Sensor (SOLVED)

johnnytoxic

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Just to give you my experience of an issue and fix.

Clicking the Aircon switch didn't engage the clutch.
Checked everything relays, fuses.

For me, it was the Aircon Pressure Sensor.
£14 replacement.
You just need to take the front bumper off and then it is easily visible near the drivers side.

There is no valve on it so the gas would need to be drained before taking it off.
 

csak1981

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I've got same problem and my hds is saying short in pressure sensor circuit. I know compressor is fine as i can activate it through hds.
Just didn't want to try replacing sensor incase there was an actual short in wiring between climate control module and sensor.
I spoke to reputable air con specialist who I used last year for a re-gas and he says its rare for the sensor to go bad on Hondas.
My workshop manual actually tells you how to diagnose the wiring to find out if the module is bad / wiring has a short or open/ or if sensor needs replaced by using a multimeter. It's a bit extra work as bumper off job and dash needs partially stripped but could save you the cost of a new sensor plus re-gas which in my case would be £120 as he was saying not to buy an aftermarket sensor as Hondas don't like them.
Thinking I'll just try sensor straight off now that you've had yours fail.
 

johnnytoxic

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I've got same problem and my hds is saying short in pressure sensor circuit. I know compressor is fine as i can activate it through hds.
Just didn't want to try replacing sensor incase there was an actual short in wiring between climate control module and sensor.
I spoke to reputable air con specialist who I used last year for a re-gas and he says its rare for the sensor to go bad on Hondas.
My workshop manual actually tells you how to diagnose the wiring to find out if the module is bad / wiring has a short or open/ or if sensor needs replaced by using a multimeter. It's a bit extra work as bumper off job and dash needs partially stripped but could save you the cost of a new sensor plus re-gas which in my case would be £120 as he was saying not to buy an aftermarket sensor as Hondas don't like them.
Thinking I'll just try sensor straight off now that you've had yours fail.
I had the same error code on the HDS by the way. Short between module and sensor.
I thought getting the climate control unit out was just as troublesome. So went for the sensor first.
I would be confident it is the sensor. I mean nothing really moves behind the unit for a short to occur.
 
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csak1981

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That's great news which would save me alot of hassle and cash so thanks for following this up.
What aftermarket sensor did you pick up? And is the system working ok with it?
The air con guy I use is as I said very reputable but if aftermarket is going to be ok then that's a £46 pound saving right there.
Aftermarket can be hit and miss so would be looking to pick up exact brand sensor you tried
Many thanks
 

johnnytoxic

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That's great news which would save me alot of hassle and cash so thanks for following this up.
What aftermarket sensor did you pick up? And is the system working ok with it?
The air con guy I use is as I said very reputable but if aftermarket is going to be ok then that's a £46 pound saving right there.
Aftermarket can be hit and miss so would be looking to pick up exact brand sensor you tried
Many thanks
It was this one. Yes working fine, colder than ever.


You can also re-gas yourself, but again I would advise not to leak the gas out :)
 
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Bounder

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I've got same problem and my hds is saying short in pressure sensor circuit. I know compressor is fine as i can activate it through hds.
Just didn't want to try replacing sensor incase there was an actual short in wiring between climate control module and sensor.
I spoke to reputable air con specialist who I used last year for a re-gas and he says its rare for the sensor to go bad on Hondas.
My workshop manual actually tells you how to diagnose the wiring to find out if the module is bad / wiring has a short or open/ or if sensor needs replaced by using a multimeter. It's a bit extra work as bumper off job and dash needs partially stripped but could save you the cost of a new sensor plus re-gas which in my case would be £120 as he was saying not to buy an aftermarket sensor as Hondas don't like them.
Thinking I'll just try sensor straight off now that you've had yours fail.
Can you post the instruction on how to check the wiring for the module please?
 

csak1981

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The check procedure is specific to the fault code that me and johnnytoxic found after plugging the hds into car. B2980-a short in the a/c pressure sensor circuit was the code.
Alot of work involved in doing the procedure for this code, bottom of dash and trim needs removed as well as bumper off. You'll save yourself alot of time and hassle if you can get checked for codes on hds.
As you were saying on the original thread that the compressor kicks in then off immediately then that suggests wiring from control unit in dash to pressure sensor is fine. If you push the a.c. button from ac/off to ac/on and compressor switches on even for a second then there is a signal coming from control unit to the compressor relay circuit.

I've still to swap my sensor out and I'm getting absolutely nothing when switching ac on from dash, no clicks, drop in revs nothing. The pressure sensor seems to have a short in it which in turn is wired straight to control unit which is why the hds is saying short in the circuit.
I'm my particular case the wiring or control unit may be at fault and I may ultimately need to change out the control unit but as johnnytoxic was lucky in that changing the sensor has fixed the issue I'm going down that road rather than the work involved in doing the checks on the control unit.

I would strongly suggest checking for codes first then go from there.
 
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Neilos84

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Also, ive just changed the control unit in the dash, it is literally a 5 minute job. Just search accord radio removal
 

csak1981

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Hds is dealer level diagnostics on laptop.
If your compressor is engaging you may just be low on refrigerant.
Did you swap out your control unit to try fix your air con not working?
 

Neilos84

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Its been checked by a ac specialist. Cant remember the amount but had 470 odd of fresh gas. As i had it re gassed a few month back, he checked the wiring to some valve/bypass behind the front bumper, and he said there was a dead wire coming from there to the control module, so they suspected it might be that, so i tried a second hand one, highly unlikly it also has the same problem. Wounder if i should try replace pressure sensor
 

csak1981

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Mine is back up and running after replacing pressure switch. When you said compressor is engaging is that when the aircon guy applied voltage to compressor or when switching aircon on dashboard?
As i mentioned above i diagnosed my compressor as good by activating it through hds.
I wasn't getting any action when switch on with button on dash, I could of started checking wiring between control unit and pressure switch but decided to do what johnnytoxic did as he had the exact same error code as me (a short in the a/c pressure sensor circuit)
I would say the cheapest option for you going forward is new pressure switch and take the switch with you to get fitted by aircon guy as he'll need to degas then regas the system. You won't need to delete any error codes, if the switch is the problem then the ac will switch on.

If you do have a dead wire between the pressure switch and control unit then changing out the control unit will not fix it as the problem is in the wiring loom between the two.
 

Neilos84

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Yea i can hear the compressor turn on with the button, the radiator fans also come on. The guy who checked it is an auto electrician and aircon specialist. There is a black rubber pipe going to the compressor on the LOW side which when aircon is turned on, gets sucked cloesed.
 

Neilos84

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Seems my compressor is sucking the lowside rubber pipe closed. Middle highside pipe is really cold to touch, at the back of the engine bay
 

Neilos84

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Mine is back up and running after replacing pressure switch. When you said compressor is engaging is that when the aircon guy applied voltage to compressor or when switching aircon on dashboard?
As i mentioned above i diagnosed my compressor as good by activating it through hds.
I wasn't getting any action when switch on with button on dash, I could of started checking wiring between control unit and pressure switch but decided to do what johnnytoxic did as he had the exact same error code as me (a short in the a/c pressure sensor circuit)
I would say the cheapest option for you going forward is new pressure switch and take the switch with you to get fitted by aircon guy as he'll need to degas then regas the system. You won't need to delete any error codes, if the switch is the problem then the ac will switch on.

If you do have a dead wire between the pressure switch and control unit then changing out the control unit will not fix it as the problem is in the wiring loom between the two.
Do you know if the pressure switch has any control over the activation of the expansion valve, as the guy said that is not getting signal, hence why he suspects the control unit. Said he manually powered the valve and had it open and the ac running fine. Wheather he has or is just telling lies, i dont know
 

MrDen

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Hello guys. Was reading a lot, but can't find an answer for my problem. My a/c is not switching on. OBD scanner is showing error B1031, ultrasonic sensor malfunction. In garage they told that they can't find this sensor. Can you please help me, what sensor is that?
 
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