wk9k

I have a 2000 civic EX y8. I can hear the clutch switching on and off on and off like every 2 seconds and it keeps doing it until I turn it off or turn the blower fan on HIGH or give it gas ....

It only seems to do this when the blower fan is turned to LOW setting and when I come to a stop after driving the car and im at idle...

It blows pretty cool air when im driving and its like around 100F~ around here.

Where should I start my troubleshooting? Thanks

b20c5eg

sounds like the refrigerant is getting low and the low pressure switch it cutting it out so the evaporator doesnt freeze. check your pressures and see if the low side it getting down to 25 or 20 when it cuts out.

wk9k

Ok, thanks for the reply. Do I need to get the manifold gauge kit. Or just the low side gauge u can buy by itself.

Former User

Test the A/C thermostat plugged into the evaporator.

b20c5eg

manifold guage would be better but that little charge hose with the build on pressure guage will work for what we're looking for. It should only be like $15 or so at your local part store. As far as the thermostatic expansion valve, I have no idea how to test it. I've never seen one go bad. I know its a lot of work just to get to it. I still think your system is just a little low from a small leak somewhere.

Former User

Keep in mind that the OP's A/C blows cold. Slightly low refrigerant would not cause the problem described by the OP because the pressure switch only turns off the compressor clutch when the system pressure is extremely low, essentially empty.

The problem could be caused by excessive pressure, such as might be caused by a bad condenser or the condenser fan not working. But again, this is not the best fit because the OP is not experiencing any cooling problems.

This is why I think the OP should test the A/C thermostat.

Testing the thermostat is a bit complicated, so you might want to try this test:

When the problem is happening,
1) Unplug the A/C thermostat 3P connector and short the Blu/Wht wire terminal to the Blu/Red wire terminal in the connector.
2) Turn on A/C to see whether the problem is eliminated.

b20c5eg

I'm going to have to disagree. I could be wrong, wouldnt be my 1st time for sure. I'm sure the ac will still blow cool, maybe even cold with low refrigerant because the low side will have such low pressure. It makes it so cold the evaproator can freeze and crack (thats what the low pressure switch or clutch cycling switch is for). Most low pressure cut off switch are between 20 and 25 psi, which doesnt have to mean the system is empty, just low (sometimes only a little bit low). Also, when you say ac thermostat, what do you mean. I thought you was saying the t.e.v. at the evaporator. What is an ac thermostat?

b20c5eg

It also makes sense that it doesnt cycle as fast when the blower is turned on high. really sounds like low r134a

wk9k

Yea the condensor fan comes on as soon as I turn the a/c on. I just went out and turned the car on with the a/c on blower fan on low and the condensor fan came on. Its very hot and humid outside so the a/c was not blowing cold air..very slightly cool. The clutch didnt do that crazy on off on off thing. I havent driven it any today but like I said it seems too do it after ive driven for a few min and then come to a stop and let it idle.
When I first got this car it had 15k miles. My first ac compressor went out at around 120k miles and I had a mech put a new one in.. I told him it was doing this problem (on off on off clutch) and he hooked it up and vacuumed all the refrigerant out and filled it back up. He said it wasnt holding vacuum or something like that anyways he did say something about there was a small leak and he did put a new valve on on there and said it should do good just keep a check on it just I might have to top it off after a while... Its been a while I now have 209k miles and its doin it again.

I looked in my honda civic manual and yes Ron it is kinda complicated to test the a/c thermostat lol.

Ron: when u say short the Blu/Wht wire terminal to the Blu/Red wire terminal in the connector. How exactly am I to short the blu/wht to the blu/red? sticking a paperclip from one terminal to the other?

Also when the clutch is switching on and off rapidly like this every 2 seconds and wont stop will that hurt the compressor or anything while im shorting the blu/wht to blu/red on the a/c thermostat?

b20c5eg: Im going to check the pressure also just to see where its at. I have been meaning to get a gauge for the a/c so imma go ahead and get the whole manifold gauge when I get paid this week..in the meantime I will try Rons test since its free at the moment although u may be right about the low on refrigerant.

thanks!

Former User

1) The low cut off for the A/C pressure switch is 28 psi.

2) The pressure switch is located on the high side, not the low side.

3) Static refrigerant pressure (A/C off) in the A/C system at normal outside temperatures is about 100 psi. You can remove most of the refrigerant from a fully charged A/C system without ever affecting the static pressure because the refrigerant exists in both the gas and liquid states. Static pressure is unaffected by the loss because liquid refrigerant quickly replenishes the lost refrigerant gas. Static pressure only begins to drop after refrigerant gas removal has depleted all refrigerant liquid and only refrigerant gas remains. Therefore, at the point where the high-side pressure is near or below 28 PSI, the system is for all intents and purposes empty and will no longer have the capacity to cool.



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Former User

This^ would be fine.


A brief test to see if the problem goes away should not be a problem. The A/C thermostat's only purpose is to prevent the evaporator from turning into a block of ice. The test is just bypassing the A/C thermostat to see whether it may be causing the problem.

If the A/C thermostat is fine, I would recommend that you next measure the clearance between the clutch armature plate and pulley.

http://s639.photobucket.com/albums/u...cture_4762.jpg

dwn134@gmail.co

1st step in any a/c checking is checking the low AND the high pressures both can cause the compressor to turn off any thing lower than 28 and higher than 350 should cut power to it chech that and give us further data please