Hi,
When I turn on my defroster, I hear a clicking--like a turn signal or something--coming from the dash or firewall. It does it as long as the defroster is on, and the idle fluxuates some too. It didn't do this until I tried to fill the air conditioner with r134 this summer. My air conditioning by the way still does not work.
The defroster works, its just a little annoying to hear the clicking.
Any ideas?

 

Your idle is unstable and this started after you tried filling the system with R134. This leads me to a thought that your A/C compressor clutch is kicking in momentarily but disengaging right away because of lack of cooling medium in the system (R134).

If you turn on your A/C (not the defroster), do you hear the same clicking?

Did you get out of the car and raise the hood to check whether the clicking was coming from the A/C compressor?

Hope this helps.
Lou

 

I had a similar problem with the compressor clutch kicking on and off when I had almost no pressure in the A/C system. My RPM's would go up and the voltage would drop whenever the compressor clutch kicked in while I had the A/C on. Took the A/C system apart, flushed it out, replaced the orifice tube & O-rings, vacuumed the system, serviced the system with R-134A and have not had the problem since. I also replaced the high and low side pressure switchs for good measure. BTW, A/C will now almost freeze me if I have it set too high.

 

I never got my A/C system full. It stopped accepting 134 after about 1/2 can. The compressor does click on and off, however about 4-5 times a minute, and the other clicking is about 100-120 times a minute. Sounds like its in front of the guages somewhere. I am going to flush and redo the cooling system in the spring anyway, so maybe that'll fix it. I just don't want to melt down anything in the meantime!