View Full Version : A/C Issues.. help! S14 KA.
Ruby240
08-03-2010, 02:27 PM
I have searched, but have not found answers that's why I'm posting.
A/C has a full charge. Compressor clutch does not engage, unless I manually jump it at the Triple Pressure Switch (new). This is the only way I can get it to turn on, but once it is jumped, air blows COLD in the car.
What components would keep my a/c clutch from engaging, and how do I check those parts? I keep seeing Thermo Control Amp (I know where it is, but not how to test it), and the Ambient Temp Sensor (again, I just don't know how to test it).
I haven't changed out the drier (I know I should have, but I didn't) yet. Would this cause the Triple Pressure Switch to not send a signal to turn on the a/c clutch?
The expansion valve (inside the evaporator box), how often do these go bad? I know they are very hard to diagnose when the system isn't working, but with the a/c blowing very cold with the compressor jumped, I don't think it is the issue. But just covering the bases.
What about the fuse box under the hood? All of my fuses and relays are good. But, on the far right side of the fuse box under the hood, it looks like I'm missing a array for fuses. One of these does say A/C and takes a 7.5a fuse.
I've exhausted all of my options and use of my own knowledge, that is why I'm turning to you guys.
KrazyS13
08-03-2010, 02:56 PM
I had a expansion valve start acting up and doing strange stuff like that on my Subaru. My fix was to add some PAG oil and it cleared it right up. Did you put a oil charge in when you recharged?
Ruby240
08-03-2010, 04:23 PM
The system was professionally filled. I don't have the equipment to draw a vacuum. Top off cans generally don't work very well.
OLDSCHOOLRICE
08-04-2010, 08:01 AM
Your refrigerant circuit sounds fine(ie. compressor, expansion valve, condensor, evaporator....) if when you directly power up the compressor clutch the system blows cold air.
You most likely have an electrical issue with either a sensor/switch or the pushbutton unit. Unfortunately, I am not familiar with which sensors/switches these systems use.
It probably also wouldn't hurt to slap a 7.5amp fuse in that empty slot and see if the clutch engages when the a/c is turned on.
Ruby240
08-04-2010, 02:43 PM
I can't put a 7.5a fuse in the empty slot, cause there is no slot. It's missing the entire block. I'm leaning away from the HVAC control, as the a/c button lights up as it should, and I don't have any problems with the venting doors not working accordingly. But, I'm not ruling it out, I have another control set I'll swap into there just to rule it out though.
I'm wondering if it could be my Drier. While I didn't replace it, I now know that I should have. As it had been opened up to the elements, for an undermined amount of time. I'm beginning to wonder if this is causing the triple pressure switch from engaging the clutch.
I really would like to know how I can bypass the Ambient Temp Sensor, and the Thermo Control Amplifier, to rule those out as being bad units.
Ruby240
08-05-2010, 04:48 PM
Well, I'm going to change out the Thermo Control Amp. Problem is, I can't get the probe out. I don't want to yank on it and rip apart my evaporator core. Can I just cut off the lead and stuff it back in the box? Then just clip the new lead into the core? I opened the box, but not very far. I managed to get it open far enough to stick my hand in there, but not far enough where I could reach all the way back to the probe.
Anybody know of a better way?
OLDSCHOOLRICE
08-06-2010, 12:21 AM
Again, I'm not familiar with the sensors/switches used on s-chassis a/c systems, but I would say that based on your description it's an electrical issue. If when you "jump" the clutch, it engages and your system blows cold, then the fault is in the circuit that tells the clutch to, or prevents the clutch from engaging.
Your drier does not have any effect on the electrical circuit. Your drier's job is to remove the moisture from inside the refrigerant circuit.
KrazyS13
08-06-2010, 06:47 AM
That is the same reason why I mentioned the expansion valve. When the expansion valve gets stuck closed it's not allowing the 134 to circulate through the evaporator causing pressure to build therefore tripping the pressure switch cause there is too much pressure. Jumping the clutch will get the AC working but the lines have too much pressure. In this case if you jumped the clutch and left it like that for too long than you could blow out a ac line. Could take a year to blow, could take 10 minutes. Probably sooner than later.
When my Subaru's EV was acting up you could hear it open/close. One day with my ac on it made the noise and opened, then went to close but got stuck and it blew my A/C line while driving dowm a busy street..lol Might not pertain to your exact situation but I figured I'd share for some thought.
Oh yeah, I've filled many older A/C systems(thats been sitting unused) successfully with cans from the auto parts store so I don't know why you'd say that. Just because it comes from the autoparts store doesn't mean it shouldn't be charged correctly(i think alot of people assume because its a "kit" they can just throw it in there and expect it to work). I pull a vacuum and use a manifold gauge set to determine proper pressures and I've always had good luck.
Hope you get it figured out, I dont know where you live but the heat wave we've had here the past couple of weeks I'd be dying without my AC!
When I couldn't turn on my AC a few years back, I had to replace the ECU. For some strange reason the ECU wasn't energizing the AC Relay that actually turns on the AC compressor.
check out HA-A/C-02 page in the FSM where you can see the schematic diagram.
Although the ECU worked w/o problems, it just wasn't turning on my AC.
Ruby240
08-06-2010, 03:41 PM
When changing out the expansion valve, does the a/c system need to be evacuated?
OLDSCHOOLRICE
08-07-2010, 08:37 AM
That is the same reason why I mentioned the expansion valve. When the expansion valve gets stuck closed it's not allowing the 134 to circulate through the evaporator causing pressure to build therefore tripping the pressure switch cause there is too much pressure. Jumping the clutch will get the AC working but the lines have too much pressure. In this case if you jumped the clutch and left it like that for too long than you could blow out a ac line. Could take a year to blow, could take 10 minutes. Probably sooner than later.
I understand what your saying, and I agree that an expansion valve could cause the pressure switch to see high pressures, eventually causing the system to stop operating the clutch.
But in this guys situation, he's saying that the clutch won't engage at all. If the expansion valve was sticking or restricted, the clutch would have to engage for the system to build up excessive pressure on the high side. At which point the pressure sensor would recognize this and cause the clutch to disengage.
Based on your description, your problem sounds electrical(ie. switch, sensor, relay, or wiring).
OLDSCHOOLRICE
08-07-2010, 08:40 AM
When changing out the expansion valve, does the a/c system need to be evacuated?
Yes, the expansion valve is inline with the refrigerant circuit. You would also have to evacuate/recharge the system if you were replacing a sensor that taps into the circuit.
Ruby240
08-07-2010, 02:02 PM
Well, sounds like it's all boiling down to my Thermo Control Amp.
I think I have ruled out the Triple Pressure Switch all together finally. Just jumped terminal 3 from the relay, and the clutch engaged. So power is going through the pressure switch, and it is reacting as it should. Now if I could figure out a way to bypass the Thermo Amp, I would know for sure if it is bad or not.
Ruby240
08-28-2010, 02:38 PM
Alright, STILL no working A/C. Triple Pressure Switch and the Thermo Amp have both been replaced. I'm pulling out my hair here and I don't know WTF is wrong with the system. The relay is good, as I fail to believe all of them I've tested are bad. I don't know what to do at this point, except take the car to a shop to have them go through the entire system. Problem is, I can't. I can't be left without a car for any period of time. I can take it somewhere and wait, but I can't just leave my car at a shop for days on end.
What has been done:
Full Charge
New Triple Pressure Switch
Replaced Thermo Control Amp.
Most of the info is the same as it is before in this same thread. I can force the compressor to turn on by jumping the relay to the battery off the #3 terminal, as well as the #3 to #5 terminal for the relay. And I can force the compressor to turn on from the TPS by jumping it, but those are the only ways.
I'm assuming that my problem has to do with wiring or a circuit somewhere. But where does the signal come from that tells the relay to close the circuit to turn on the compressor?
S14DB
08-28-2010, 02:49 PM
Do you have Gauges?
Did you check the pressure at the TPS when you replaced it?
Ruby240
08-29-2010, 03:28 PM
I don't have gauges, but when the system was filled the pressures were within spec. I'm still not ruling out the Drier, as it's about the only thing I haven't replaced except the lines and the compressor.
S14DB
08-29-2010, 03:59 PM
If it works when you jump the TPS and you put a new TPS in there. I would say the valve in the dryer is sticking.
Best bet is to evacuate the system and put a new dryer in. Then have them test the system to make sure the pressers are right while running.
Ruby240
08-30-2010, 08:39 PM
Thanks. Looks like I'm gonna be picking up a Drier when I get paid again..
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