A/C Problem

[system-f]

Alrighty I have a problem with the A/C clutch engaging and disengaging very rapidly only after the A/C has been used for awhile. What I have done to diagnos the problems so far.

Ran a power line to the A/C clutch so I could manualy turn it off and on, the problem was resolved, so it's not the clutch.

Checked the relay, it's fine.

Replaced the Delay control unit found on Fuel injected cars, not the problem either.

I have noticed that if I turn the fan up higher the problem goes away a bit longer.... which makes me think it might be the fan resistor? (fan has to be on for the a/c to work) or even the temperature control unit hooked to the evaporator?

anyone had this problem? it's quiet anoying driving down the highway and having the a/c shut on off on off on off as fast as it can, and probably not good for the clutch in the compressor (less than 10k miles on it).

[88LXi/87CRXSi]

system-f. first, to the board! Now I haven't had that problem but, I can tell you that the a/c clutch circuit doesn't use the fan resister. There is a seperate contact, that closes to ground, once the fan switch is in any position except "off". So, the blower switch itself, the a/c thermostat, (which you mentioned), the a/c pressure cutout switch, (open below 30 psi, left front of engine compartment, behind headlight), or even the a/c diode box could be screwing up. Maybe even a bad connection to one of those!
There are some folks on here, that are really good with electronics, not me, that will hopefully jump in to suggest more likely causes.

[system-f]

Thanks for the help, I replaced the 'diode box' or delay control unit, and I know it's not the preasure switch as I bridged that with wire (per the manual). If for some reason the fan resistor has lost contact when hot then the a/c system will see the fan in the off position and shut off. When the car was at idle the clutch was cutting in and out as usual after the a/c system has been used and I reached under the passenger side of the dash and grabbed all the wires to the fan resistor/fan/dealy box and wiggled them, it seemed to stop. time to check for a loose connection.

[Gregg86DX]

I don't have my AC book with me, so I can't advise much, but I would take a quick look at this forum:

http://www.ackits.com/forum/index.cfm

and search on something like "rapid cycling". If you can't find anything, then just post your situation; be sure to provide all the details you can like make, model, year, tempurature, etc... They should be able to help.

Gregg

[Vinny]

you said when you hot wired the compressor directly the problem completely went away? If thats the case then you may want to change the clutch relay. Even if it checked good it may be gicving out as it heats up, the resistance could be increasin as the heat builds up. Honestly its a fairly simple sytem. The only thing outside of a bad clutch that will cause the clutch to not work is lack of pressure in the system or lack of power to the clutch. The sedan had a VERY similar problem. I put all new parts in the system when I bought the car (compressor, condensor, evap, rec, and hoses) and toward the end of the summer the compressor would cycle at times. Pressure was fine because both fans came on (they won't if the systems low due to the pressure switch) The relay checked good so I replaced the compressor a few weeks ago. Pulled a vac on the sytem, leak checked it, and serviced it and the compressor wouldn't engage at all. No power at the clutch. I swapped the compressor relay with the hatch and works like a champ. Since its intemittent you may have to take the most likely cause and swap it, that or wait until it dies completely

[system-f]

I wished it was as simple as the compressor relay, that was my first guess...replaced it.. problem still there :/

The only thing outside of a bad clutch that will cause the clutch to not work is lack of pressure in the system or lack of power to the clutch.

THe a/c system in my 87 uses a temp unit on the evaporator to turn the system on and off autmoatically when it gets too cold to prevent freeze up *one of the preventions* if this sensor on the evaporator is bad it will cause this problem in theory. The delay control unit on the fuel injected models brings our A/C system from simple to not as simple as it could be.

[accordlxi2.0]

yea don't worry about it, the same thing with mine when i have it blasting the compressor stay's on but if i turn the fan down then depending on the fan speed the cycle varies, plus if the engine reaches a certain point when the engine's to cold the fan's and/or compressor won't turn on.

[Vinny]

did you replace the round relay by the radiator relay or the square diode? The delay timer is an very simple test. As far as the thermostat goes use a thermometer in the vent to see if you can gauge approximately what the temp is when its cutting out. If it cuts out as it gets colder than I'd look toward the thermostat

[system-f]

I replaced both the under hood relay and the delay control box... It's so cheap for parts I am probably just going to go to the pic N pull and pull everything under dash for it. You know, after 240kmiles it could be that there is just a large quantity of dirt on the little thermo unit on the evaporator...not sure. Ahhh true, it does cut out when less cool air is being pulled off the evaporator ie. when the fan is on a lower setting it cuts out more, cooler evaporate.. Oh yeah, nice accord Vinny

[system-f]

So I found the culprit. Its the A/C cycle swith/thermostat.



notice how dirty it is ?? it still might be bad, but I will clean it first.



I also hooked a light up to the A/C system to let me know when the cluthc is engaging, before the delay control unit and it was blinking on and off after a certain period.

[Vinny]

well good to hear yopu found it. i just got mine up and working on the hatch. Yesterdays outside temp 91, temp out of the ducts, 36

[87AccordsterLx]

well good to hear yopu found it. i just got mine up and working on the hatch. Yesterdays outside temp 91, temp out of the ducts, 36

I can vouch to that... that R12 was damn cold Vinny....

It reminds me of when my uncle did it to his old Dakota... that thing would throw ice out the vents... no lie.