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Low Vent Temp

73Wagoneer on Sat June 27, 2009 10:07 PM User is offline

Year: 94
Make: Honda
Model: Civic
Engine Size: 1.6
Refrigerant Type: 134
Ambient Temp: 95
Pressure Low: 40
Pressure High: 200

I replaced the evap core, expansion valve and drier last summer because the evap core was leaking, before the install when the A/C was working I had vent temps of 40 on a 90+ day. since then I have pulled a vacuum and recharge 3 times and I cannot get the vent temp below 50.

Am I missing something here? could the compressor be weak, it seems like the compressor is shutting off too soon, should I try the old expansion valve?

I really do not know what is goin on with this A/C

Thanks in advance

Rob

temp control valve is working fine

94RX-7 on Sat June 27, 2009 10:56 PM User is offline

You're saying the compressor is shutting off too soon? Seems to me that could be one of three things:

The engine computer is shutting it off for some reason (not likely)
The system is low on refrigerant and is shutting down on low pressure (again, not likely with the pressures you posted)
The temperature sensor on the evaporator (freeze prevention) is shutting it off at too high a temperature (my money is on this being the problem)

The low side pressure you posted does seem a touch high, but if the compressor is being cycled on and off with 50 degree vent temps I wouldn't worry about that just yet.

73Wagoneer on Sat June 27, 2009 11:21 PM User is offline

I am assuming the temperture sensor is the Expansion valve, it is a new one, do you think I should put the old one back on, I replaced it with a new one because I was replacing the evap anyways.

the systems call for 17-19 oz of 134, I added one 12 oz can and a little more than half of another one.

Before I posted, I was tempted to re install the old expansion valve, but really dreaded tearing everything apart again.

94RX-7 on Sat June 27, 2009 11:40 PM User is offline

The temperature sensor is separate from the expansion valve.

You're sure the compressor is cycling on and off?

94RX-7 on Sun June 28, 2009 12:11 AM User is offline

The temperature switch is number 6 in this diagram:

73Wagoneer on Sun June 28, 2009 9:48 AM User is offline

Ok I know where that sensor is, is there a way to check it???

compressor is cycling off and on, I get vent temp of 50 degrees

Edited: Sun June 28, 2009 at 9:49 AM by 73Wagoneer

94RX-7 on Sun June 28, 2009 10:33 AM User is offline

You can usually hear that type of sensor click as it turns on and off if you can hear it clicking on and off as the compressor cycles on and off then that's more than likely your culprit.

Check and see if there's a screw for adjusting the switch...some are adjustable. If the adjustment is hard to get to, I would just replace it since you may have to make multiple adjustments if you set it too low and the evaporator starts freezing up.

73Wagoneer on Sun June 28, 2009 10:41 AM User is offline

i know there is no adjustment on it, I remember having to unplug this sensor to remove the evap, and it looks like this will be a dealer item, as autozone/orielly doenst have them

are you saying if it clicks on and off with the compressor it bad??? not sure I understand


Edited: Sun June 28, 2009 at 10:43 AM by 73Wagoneer

94RX-7 on Sun June 28, 2009 11:11 AM User is offline

If you hear the switch click, and the compressor shuts off at the same time, and your vent temps are only in the 50s, then that implies that the switch is turning the compressor off at too high a temperature, and is not doing it's job properly.

The job of the switch is to keep the evaporator from freezing up. It should be shutting off the compressor when the evaporator temperature gets down into the mid to low 30s. I suspect it is shutting down the compressor in the mid to upper 40s.

73Wagoneer on Sun June 28, 2009 1:07 PM User is offline

hmmmm, well i guess i can get a switch and try that

94RX-7 on Sun June 28, 2009 3:23 PM User is offline

You can also try temporarily bypassing the switch and see if the vent temps come down.

73Wagoneer on Sun June 28, 2009 3:58 PM User is offline

If I disconnect the switch the A/C comp turns off, I have also search on line for a temperature control switch, I cant find it? Any help on locating one???


any other ideas, I checked the heater valve again, even disconnected the wire, and closed it manual, it was closed when hooked up to the wire, seems like everything else is working fine, the low pressure line even sweats and is cold to the touch

94RX-7 on Sun June 28, 2009 9:19 PM User is offline

I can't say for sure without looking at the wiring diagrams for this car, but probably what you need to do to bypass the switch is unplug both wires and then jumper them together. If you do this and fry half your car's electronics I'm not liable.

Check with AMA to see if they can get the switch for you. If they can't then I'll tell you what site will be able to get you an OEM Honda part.

73Wagoneer on Sun June 28, 2009 9:59 PM User is offline

I believe the thermostat switch is working properly, I was able to separate the evap housing about an inch, I put my thermometer in there with the A/C on, it was 30 degrees, I also moved the themostate end, the one that is mounted on the fins of the evap, I moved it away from the evap a little, it brought my vent temps down to 40, so I am thinking this was the prob, well see

I think with 30 degrees coming out of the evap I cant complain, hopfully by moving that sender the evap wont freeze.

Thanks for all the input, and I almost did jump that switch, but because it had 3 wires on it, I said Ill wait. Glad I did

Edited: Sun June 28, 2009 at 10:01 PM by 73Wagoneer

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