Civic Idle Issue with A/C On

I'd brought this up a couple weeks ago, but wanted to run it
by y'all again with different wording.

Sometimes, maybe 1/3 of the time, when I'm stopped at a red
light, and only when the A/C is on, I notice my RPMs just going up a
couple hundred, down a couple hundred every second or so as my A/C
compressor clicks on and off.... click, click, click, click... on,
off, on, off...

Click... rpms go up as the compressor turns on
Click... rpms go down as the compressor turns off
Click... rpms go up as the compressor turns on
Click... rpms go down as the compressor turns off
Click... rpms go up as the compressor turns on
Click... rpms go down as the compressor turns off
Click... rpms go up as the compressor turns on
Click... rpms go down as the compressor turns off
Click... rpms go up as the compressor turns on
Click... rpms go down as the compressor turns off

Over and over. I don't seem to notice it much while driving,
just at stops.

What do you think the issue is? Vaccuum leak? Bad
Compressor? I want to have this looked at, any idea what that should
run me at the mechanic?

I'm asking again because I did have a bad A/C control unit
(the box next to the radio that controls fan speed, temperature, etc).
I just replaced that unit today. While it fixed the problems of knobs
that didn't work anymore, I wanted to make sure it was not related to
the click click click click issue above.

Thanks!

 

A low refrigerent level can cause short cycle times.

JT

 

Dang - I missed that point the first time I read it. "Every second or so" is
a big red flag for low refrigerant. Time to take a trip to an auto A/C
professional. R-134a is tricky stuff to try to recharge yourself, although
at this point I'd venture the total charge is just a few ounces.

Mike

 

The car is a 1999 (made in '98) so would you expect that there is a
leak in the system? The coolant doesn't just evaporate over time,
does it?

I will check into have it recharged, but I'm wondering if it might
just leak out again.

Thanks a lot!!

 

Leakage of refrigerant in cars is a common occurrence. It's the *rate*
of leakage that can be of concern. "Topping off" every three years or
so is (to me) the benchmark for action should it occur quicker than that...

JT

 

Yep - three years is not good. A professional will evacuate the old
refrigerant for reuse, and will pull a vacuum on the system to remove
incondensables and water, and to test for leaks. Leaks have to be fixed
before recharging.

Mike

 

Understood fellas, thanks for all the info. I'll have it fixed up
this weekend.

 

There is a sight glass on (or maybe near) the drier thing, which IIRC
is a sort of beer can sized thing sitting vertically on the driver's
side of the radiator support, plumbed into the AC line. It's a little
window, about the size of a dime, into the line, facing up. With the
AC on full blast, you can see what's going on in the line. There
should be essentially no bubbles; if there are bubbles, then the
pressure is low and needs recharging. If there are no bubbles, then it
is either full, which is good, or empty, which you should be able to
figure out by the fact that you have no AC.

Car ACs leak a lot, because of all the hoses necessary to connect from
the body mounted stuff to the engine mounted stuff. When manufacturers
go to an all electric system they can just seal it all up, like in a
refrigerator or a home AC, and that oughta solve that problem.

 

So I took my 99 Civic into a different dealer to have the work done.
Oil change, spark plugs, as well as the A/C work.

The problem with the A/c is (again) that sometimes the compressor
clicks on and off every second or so while I'm idling. I've also had
toruble with the until that controls the fan speed, temperature, and
vents. The problem is sometimes the fan won't come on. So the
compressor may turn on, but no air blows from the vents.

Anyway, the dealer told me that the problem with the compressor was
that it was OVER FULL. In 7 years, I don't believe I've ever had any
maintenance done on the A/C system, never needed to be recharged or
anything. Makes me wonder if the previous Honda dealer that did the
last oil change tried to jack with it in hopes of having me return for
service sooner rather than later. They released pressure in there and
put it at the proper level.

As far as the control unit issue, it was working when I took it in
today (I replaced the control unit with a new one last week. Cost me
$300 to find out that wasn't the problem). So they weren't able to
really diagnose any issue there.

What do you folks think the issue with the control unit might be? Bad
blower?

Thanks!