1999 Honda Civic MB6 shaped 1.8 VTi - Air Conditioning is cycling on and off - Rissy

My question is related to the Air Conditioning for my car. For years, the AC has never been working on my car. I've finally, years later, just finished getting the AC up and running again. Bought a new dryer, condensor and schrader valves for it. The question i've got though, is related to the characteristics of the AC running now, since I can't remember how it ran many years ago. Is it normal for the compressor to clutch in and out repeatedly every 20-30 seconds once the temperature has got near to its expected low point of operation? Right now, this is what is happening with my car, but I don't know if it's normal or not. My thinking is that it might be temperature related, meaning the bulb on the expansion valve is causing the system to disengage to stop the evaporator from freezing. I thought maybe it might have been a low, or high pressure trip, but when you look at the system with the manifold gauge set, the needles look ok, and stay consistent, only changing when the compressor changes state from clutched in and clutched out. Can anyone out there make comment to whether this is normal or not? Is the compressor supposed to stay clutched in all the time once the AC button has been pressed in the cabin or toggle as mine is doing? As a reminder, mine seems to stay on all the time UNTIL the temperature gets to a certain point, then starts clutching in and out repeatedly. I also don't know if the expansion valve is supposed to change state in an analogue fashion or a digital one? Does the expansion valve on this car simply open and close its aperture or is it supposed to vary the degree to which the aperture is open/closed slowly?

It's annoying, as it causes a lurch demand on the engine, and causes the revs to drop a bit every time it clutches in, which is really annoying as if it happens when i change gear, it can cause quite a hiccup if the two operations coincide with each other...

Work carried out so far:

Replaced Dryer, Condensor and schrader valves, then vacuumed system to very good vacuum for about 1 hour, then regassed with 600g of R134A gas (system has an unknown quantity of PAG oil in it too)

...any help?

Rissy

1999 Honda Civic MB6 shaped 1.8 VTi - Air Conditioning is cycling on and off - elekie&a/c doctor

This is normal operation for a system of this type.The system uses a cycling clutch circuit controlled through the electronics and a thermostat in the cabin evaporator.It is an old fashioned system of operation ,but it is simple and it works.However the downside is the on/off load on the engine.The expansion valve is totally mechanical and works according to the load/demand for cooling.it is basically a variable rate version of the nozzle you would find on the top of an aerosol can.hth

Edited by elekie&a/c doctor on 12/07/2013 at 18:21

1999 Honda Civic MB6 shaped 1.8 VTi - Air Conditioning is cycling on and off - Rissy

Thank you so much for your feedback, most appreciated. This means that, despite all telling me I was wasting my time and money, that i've succeeded in getting the system running again. Yey me!

Another question I have, is to do with the quantities of oil and refrigerant gas for my car.

I first filled the system, and wasn't happy with the cycling (still thinking at this point that this was wrong, and shouldn't be doing it). SO....I evactuated the whole system again, and separated the recovered oil from the system. I separated around 38 grams of the stuff. It was at this point I replaced the dryer for new (the old one came out bone dry!?), and checked the condensor for blockages (nothing in thecondensor either). I then put the system back together again and recharged. This time though, I did NOT put any of the recovered oil back in the system again. I left it out. My thinking being that maybe there could have been too much oil too. The bottom line is, I have no idea how much oil is in my system now. The compressor is original, so is all the piping, and evaporator and expansion valve. The "new" condensor was off another car, and the dryer was the only part which was brand new. Do you think i've done the right thing here? The only other piece of information I can add is that the first time I filled the system, I went through TWO cannisters of Halfords self recharge gas and oil mixed. Too much I think, but just kept going, trying to get the system to stop switching in and out like it does. When you look at the sight glass on the fixing on the top of the dryer, you can see green (luminescent oil) which seems to rise and fall slightly according to the compressor clutching in and out, and when it gets to its high point in the glass, it goes almost frothy in appearance....!? I don't know if this is normal or not?

Also, the quantity of gas in grams. What is it supposed to be? I put back in 600 grams because my only source was an American site, saying that their equivalent cars took between 550 and 650 grams. So I went half way between, but still don't know the actual definitive answer?

I would really appreciate more feedback, thanks. :-)

Rissy.

1999 Honda Civic MB6 shaped 1.8 VTi - Air Conditioning is cycling on and off - elekie&a/c doctor

So far so good.The charge capacity of gas is 600-650 gms.The oil capacity of the complete system is 140 ml,but is obviously very difficult to assess the amount in the system without completly dismantling everything and draining the oil from the pump.It would be nice to get the 38 ml back in the system,but as you have already done a diy top up,this may not be required.The sight glass in the dryer is a bit old school,nobody uses these any longer.There will be slight frothing as the pump cuts in ,totally normal.Looks like you done a good job.The only problem you may have ,is that the s/hand condensor may be as poor as the one you have just removed.hth

1999 Honda Civic MB6 shaped 1.8 VTi - Air Conditioning is cycling on and off - Rissy

Excellent news! THANKS! I'm pretty chuffed now then.

As for the condensor, the one that came off was all sagging and bowed. It was this which caused it to develop a leak very shortly after its last recharge (by a professional about 2.5 years ago) which only lasted a week (waste of my £70) This was the first time I'd had the car recharged with gas since it has last stopped working, which was maybe about 1.5 years after I bought the car in 2004. So bought the car in 2004, got to about 2005-2006 then no AC, then left it until 2010, got it recharged for the first time ever (in my ownership), got a week out of it, then complained to the chap who had done it. He then pointed at the condensor and said that was my problem, and most likely now had a leak. He said it was fine the week before when he had recharged it, so it wasn't a refund issue. I then left it until this last few weeks, where i've been doing it myself, with help from a mate who has all the kit to do it. The replacement condensor, although old, is in much better condition than my old one. It's straight, not sagging too. So fingers crossed, and if it starts leaking again, and if I suspect the second hand condensor, then it's only about £60-£70 to buy a brand new one.

Once again, thanks very much for your input on this. This is my first experience of this site, and very pleased with it too now. I'm sure i'll be back on here in no time at all with the next issue. This Civic of mine is turning into a bit of a DIY hobby project. lol! It's an amazing car, I love it, and it's only now getting to that point where things are starting to need attention to keep it on the road in a healthy condition. Not bad for a 14yr old car with 108,000 miles on the clock! Japanese, can not fault them! :-D