jimkup Posted June 8, 2006 Share Posted June 8, 2006 Howdy folks, Last year I converted my A/C system from R-12 to R134. The conversion went well & the system worked good till this summer. Initially, it blew hot air so I topped it off. All went well & with my thermometer in the vent...cruising down the highway, sometimes the temp gets as low as 43 degrees. Lately, I started noticing a "clicking" noise behind the Glove box & sometimes when this is happening, it feels like my engine is misfiring. When the "clicking" noise is happening, the A/C clutch is turning on & off. It only happens when the A/C is on (obviously) & if it is clicking & I push the Vent button, the chattering & possible misfiring stops. The clicking noise seems to start after I have been cruising down the highway a bit and is intermittent...sometimes it chatters & then it stops for a while & then it'll start again. I called my local Mechanic & he said to check the Valve? Levers under the kick panel to be sure they were closing and opening completely. I pulled off the cover & when I switch from A/C to Vent the valve-levers appear to open & close completely. I do have a set of Guages but I am not sure what the proper pressures would be on a converted system. I am thinking that either I have too little or too much (my guess) R-134, maybe causing the pressure switch to kick off the compressor. So, has anyone experienced this b4 & if so what did ya do to stop it? What should the High side pressure be with the system on and the engine at idle...ballpark? Any info or ideas would be greatly appreciated!! Thanks!!!!!! Quote Link to comment Share on other sites More sharing options...
nipper Posted June 8, 2006 Share Posted June 8, 2006 It could be electricla in nature also. Get yourself a haynes manual, as the a/c system is slightly more complicated then one woutld think (nothing you can't tackle). nipper Quote Link to comment Share on other sites More sharing options...
Legacy777 Posted June 9, 2006 Share Posted June 9, 2006 The subaru specific haynes or chiltons manuals don't tell you squat about the AC system. I would suspect you overcharged the system. On converted r12 to r134a systems, you should run about 75% of the original R12 refrigerant capacity. Did you do the conversion, or did someone else do it? Can you give details on what exactly was done? What pressures are you seeing? A book I would recommend is the Haynes Air Conditioning book. It's very good, and has a lot of info. Quote Link to comment Share on other sites More sharing options...
jimkup Posted June 9, 2006 Author Share Posted June 9, 2006 Well, I did the conversion myself & took it to my local certified sub mechanic for evacuation & charging last year. Did not have the chattering at all afterwards & then this year it was blowing hot so I charged it myself. As far as pressures...I really don't remember what they were....seemed like the low side was around 30 psi & I think the hi side was around 270 psi....but I'm not 100% sure that is correct. Last night I was gonna check the pressures, but I could not get the Hi side connector to seat on the service valve. Really pisses me off too...especially since I had it on b4. Anyway, got the low side connected & pressure was only about 10 psi. So, I'm pulling up the white flag & taking it to my Mechanic so he can get it right. Thanks for the help & I will post the fix later! Quote Link to comment Share on other sites More sharing options...
Legacy777 Posted June 9, 2006 Share Posted June 9, 2006 You're welcome. Let us know what the final outcome is. Quote Link to comment Share on other sites More sharing options...
jimkup Posted June 30, 2006 Author Share Posted June 30, 2006 ok, I think I found it. I replaced the A/C clutch relay & it seemed to help...for only a short while. Thanks to previous posts & alot of searching, I found someone that mentioned a small "black box" about 1" wide and about 3" long, just to the right of the relay, above the Evap. core box. I believe it is a temperature switch. It has two white wires on one end, that go into the evap. core box. The other end has a four wire connector on it, but only three terminals actually have a connection. If you disconnect the connector and pull on the "black box", it will silde out a little until the white wires get tight. At this point, I cut the white wires really close to the "black box". I cut and pried until I got the "black box" open, but it is hermetically sealed inside and not serviceable. So, I went to the local jy and found a junker with that switch, a pressure switch, and another device that mounts to the front of the Evap. core box. I pulled all three and the jy charged me $25, their minimum charge for parts. Went home, soldered the new "black box" to the white wires & so far it has been working great. Blows about 65 degree air...steady, & goes slightly lower on Max. I will give it a few days & if still ok, I'm gonna shoot a little more freon to it. Anyway, that seemed to fix my clicking and sometimes like a missfire. Hope this helps a few of you USMB'ers. The previous posts helped pinpoint this for me and I must say thanks! Took me a while to get it done, but now I'm chillin here in Austin and believe me it does get really hot here. Quote Link to comment Share on other sites More sharing options...
Legacy777 Posted June 30, 2006 Share Posted June 30, 2006 Glad you got it working. Yeah, being without AC in texas is just not a good idea. Mine was out last summer. It died while I was up in Austin. Driving back to Houston was no fun! Quote Link to comment Share on other sites More sharing options...
91LegLS Posted June 30, 2006 Share Posted June 30, 2006 ok, I think I found it. I replaced the A/C clutch relay & it seemed to help...for only a short while. Thanks to previous posts & alot of searching, I found someone that mentioned a small "black box" about 1" wide and about 3" long, just to the right of the relay, above the Evap. core box. I believe it is a temperature switch. It has two white wires on one end, that go into the evap. core box. The other end has a four wire connector on it, but only three terminals actually have a connection. If you disconnect the connector and pull on the "black box", it will silde out a little until the white wires get tight. At this point, I cut the white wires really close to the "black box". I cut and pried until I got the "black box" open, but it is hermetically sealed inside and not serviceable. So, I went to the local jy and found a junker with that switch, a pressure switch, and another device that mounts to the front of the Evap. core box. I pulled all three and the jy charged me $25, their minimum charge for parts. Went home, soldered the new "black box" to the white wires & so far it has been working great. Blows about 65 degree air...steady, & goes slightly lower on Max. I will give it a few days & if still ok, I'm gonna shoot a little more freon to it. Anyway, that seemed to fix my clicking and sometimes like a missfire. Hope this helps a few of you USMB'ers. The previous posts helped pinpoint this for me and I must say thanks! Took me a while to get it done, but now I'm chillin here in Austin and believe me it does get really hot here. If your A/C doesn't seem to get cold fast enough, while you're under the dash, make sure your evap core and heater core are clean. Older vehicles can accumulate debris on the core itself from outside air contamination and can slow down the amount of chilled air being sent to the vents. I recently had mine done and my car is downright frigid in about 2 minutes. Just a suggestion. Quote Link to comment Share on other sites More sharing options...
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