Author Topic: AC compressor relay??  (Read 3038 times)

herut

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AC compressor relay??
« on: July 05, 2019, 03:12:48 PM »
I have a 2012 Jazz hybrid. My AC stopped working so I bought the 4 pin relay 39794 sda A05. The jazz manual shows an under battery relay box holding 3 relays, but when I opened it, I see there are only two relays: the A05 (which I replaced), and, a 5 pin Mitsuba RC-5102. My fans go on, but my AC is not working!

Q1: was the A05 also for my compressor? If so, my compressor may be shot...
Q2: I cannot find what the RC-5102 relay is for. Is this possibly my compressor relay? Or, what other systems does it control?

Thanks!

guest4871

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Re: AC compressor relay??
« Reply #1 on: July 05, 2019, 03:33:44 PM »
Have you had the refrigerant gas level checked?

It may have stopped because the gas level has fallen too low and it has shut off to protect the system.

First thing is to check the refrigerant gas level. It may just need re gassing.

Most tyre fitters can do this for you (or Halfords or Kwik Fit).

Why do you think it is a problem with the relay?

herut

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Re: AC compressor relay??
« Reply #2 on: July 05, 2019, 05:16:27 PM »
Hi zzaj. Thank you for your reply. I suspected low freon so I first tried to fill with a diy kit, but it appeared not to be sucking the freon into the system (ie can not getting cold at all). So, based on widespread reports of relay failure for the compressor I looked online and found the A05 relay and purchased that and put it in. my fans both went on when I depressed the AC button but as far as I can tell my compressor is not engaging. since I do not have any more Freon (because I unfortunately vented some of it by accident) I will have to take it into a filler and see what they can do, but before going there I wanted to confirm whether the relay I replaced was correct for fans and compressor, and also what the five pin relay in that box is for. Thank you! 

culzean

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Re: AC compressor relay??
« Reply #3 on: July 05, 2019, 06:28:05 PM »
Hi zzaj. Thank you for your reply. I suspected low freon so I first tried to fill with a diy kit, but it appeared not to be sucking the freon into the system (ie can not getting cold at all). So, based on widespread reports of relay failure for the compressor I looked online and found the A05 relay and purchased that and put it in. my fans both went on when I depressed the AC button but as far as I can tell my compressor is not engaging. since I do not have any more Freon (because I unfortunately vented some of it by accident) I will have to take it into a filler and see what they can do, but before going there I wanted to confirm whether the relay I replaced was correct for fans and compressor, and also what the five pin relay in that box is for. Thank you!

The aircon relay is single pole 40 amp rating ( 2 large and 2 small blades )  even though clutch solenoid only draws about 4 amps it is an inductive load and sparks fly when relay turns off power to clutch, so contact is bigger to handle that.  It may be the clutch solenoid coil that has failed open circuit, or maybe the earth return wire has fallen off.  If you take aircon relay out of socket and poke a voltmeter into one of the large pin sockets  you will get 12 volts (to earth ) on one socket and the other will measure about 3.5 ohms to earth via the clutch coil,  and its earth wire, if any wires broken or coil failed you will get open circuit reading to earth. You can normally hear the clutch energise and engine note changes slightly, you can also look at lowest pulley on auxiliary drive belt at the front ( lower down than alternator pulley but vertically in line with it ) the centre of pulley with bolt heads showing wiil be stationary with aircon  off and should spin with pulley when clutch coil energised. There is also a thermal cut-out mounted on compressor with a contact in series with clutch coil, the contact is normally closed but will open if over temperature of compressor is detected, but it does automatically reset when things cool down.

There are 3 two pole ( 4 pin) relays in  fusebox concerned with aircon, one for engine fan, one for condenser fan and one for clutch coil. With the engine not running and even without ignition on you can force clutch coil to engage by shorting out the two large sockets on where the relay plugs in, you should hear a clunk as clutch pulls in,  the feed to relay contact is straight from battery via a fuse and that is why when the aircon clutch relay contact sticks closed it can drain the battery in short order when car is parked - as coil draws  3.5 to 4 amps without ignition on,  If you have the old relay you can cut the case off and plug it in and press contacts closed by hand rather than shorting with a wire.
« Last Edit: July 05, 2019, 07:50:22 PM by culzean »
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rumourjazzit

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Re: AC compressor relay??
« Reply #4 on: February 28, 2020, 03:03:34 AM »
Hi Herut!
i'm having the same problem and really keen on trying to fix it myself by changing the relay.
Now this is the stupid question.... where is the fuse box for AC?
I saw one on left hand side and has 4 slots (with one slit having 5 pin relay, guessing this is for starter?)
Really appreciate if you can let me know where to find this fuse box so i can change my AC relay! many thanks

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