Need an A/C guru

I would imagine that you are getting 12v to the compressor. And with those readings it isn't the expansion valve, for the low side would be very low (think 15psi or less).

I'd say that the clutch isn't engaging. You can either buy a new clutch or just get a new Denso compressor. I'd choose the latter.
 
If the clutch was the issue, then why would it engage when I used a jumper wire at the high/low switch? It's too hot in this Texas heat to crawl under it right now. I'll check for 12V at the compressor later tonight when it cools down. I just don't want to start throwing money at a problem before I know what the actual problem is.

LittleCaesar said:
I would imagine that you are getting 12v to the compressor. And with those readings it isn't the expansion valve, for the low side would be very low (think 15psi or less).

I'd say that the clutch isn't engaging. You can either buy a new clutch or just get a new Denso compressor. I'd choose the latter.
Click to expand...
 
Usually a dying clutch coil is the issue. Not dead though.

If the AC is on, but the clutch isn't engaged, try bumping it with a pry bar and see if it engages then.
 
jsukey said:
If the clutch was the issue, then why would it engage when I used a jumper wire at the high/low switch? It's too hot in this Texas heat to crawl under it right now. I'll check for 12V at the compressor later tonight when it cools down. I just don't want to start throwing money at a problem before I know what the actual problem is.
Click to expand...

Maybe I'm missing something but if you bypassed the pressure switch and the clutch engages then either the switch is bad or the switch is good and it's doing it's job and the pressures are either going below 26psi or going above 455psi. Use the gauges when the system is working and observe the readings.
Also, in the picture of the gauges, how long was the system "off". Reason I ask is because the low side was 98 and the high side was 125 and if the system was off for longer than a couple minutes (or less) the pressures should have equalized. Off course, one (or both) of the gauges could be off but slow equalization would be a sign of a restriction somewhere between the low and high side, which, in all likelihood, be the expansion valve.
 
I replaced the pressure switch and had it recharged after the first time it acted up. I bypassed it with a paper clip and the compressor immediately kicked in and it started cooling. A few days later, it stopped again. Only this time, bypassing the compressor wouldn't kick on the compressor. The gauges showed it to be perfect when we put a vacuum on it and recharged it. It just started working again that evening on its own. When I took that pic of the gauges, the system hadn't worked in about 30 minutes. I pulled over to see if the lines were frozen, and then drove to the closest Autozone. The A/C was on max high when I took that pic though. Those gauges that I used were brand new. I had to take them out of the plastic, so I highly doubt they were off.


JRZEE2000TR4LTD said:
Maybe I'm missing something but if you bypassed the pressure switch and the clutch engages then either the switch is bad or the switch is good and it's doing it's job and the pressures are either going below 26psi or going above 455psi. Use the gauges when the system is working and observe the readings.
Also, in the picture of the gauges, how long was the system "off". Reason I ask is because the low side was 98 and the high side was 125 and if the system was off for longer than a couple minutes (or less) the pressures should have equalized. Off course, one (or both) of the gauges could be off but slow equalization would be a sign of a restriction somewhere between the low and high side, which, in all likelihood, be the expansion valve.
Click to expand...
 
jsukey said:
I replaced the pressure switch and had it recharged after the first time it acted up. I bypassed it with a paper clip and the compressor immediately kicked in and it started cooling. A few days later, it stopped again. Only this time, bypassing the compressor wouldn't kick on the compressor. The gauges showed it to be perfect when we put a vacuum on it and recharged it. It just started working again that evening on its own. When I took that pic of the gauges, the system hadn't worked in about 30 minutes. I pulled over to see if the lines were frozen, and then drove to the closest Autozone. The A/C was on max high when I took that pic though. Those gauges that I used were brand new. I had to take them out of the plastic, so I highly doubt they were off.
Click to expand...

When you took that pic was the clutch engaged? If so, bad compressor.
 
Those gauges are good. Made by AC Pro. Low side should be 30 to 42 and high between 190 to 235, at least on mine. Also pick up a vent thermometer to see what temps you are getting. A digital one is better.

If you replace the compressor don't forget a new drier.
 
JRZEE2000TR4LTD said:
When you took that pic was the clutch engaged? If so, bad compressor.
Click to expand...
No, the compressor wasn't engaging.

LittleCaesar said:
Those gauges are good. Made by AC Pro. Low side should be 30 to 42 and high between 190 to 235, at least on mine. Also pick up a vent thermometer to see what temps you are getting. A digital one is better.

If you replace the compressor don't forget a new drier.
Click to expand...

Those gauges were for sale at Autozone for $89.99. I was getting nothing but hot air out of the vents. We used a digital thermometer when we recharged it last week. We got it down to 46 degrees on a 90 degree and super humid day. I don't think there is anything wrong with the compressor. The clutch...maybe. I was planning on replacing the expansion valve. A new drier will be going on at the same time. May even do the evap core while I'm in there.
 
If you jump the switch and it still doesn't come on then you need to look at your climate controls. And put a test light on the wires going to your clutch.


Sent from my iPhone using Tapatalk
 
When it's not failing you need too check the pressures using the pressures Ceasar stated. When it fails, you need to check the voltage going to the compressor.
Someone else mentioned the climate controls. I have fixed almost 1000 controls and I have had 2 of them that would not activate the compressor. There's 2 PCBs inside the CCU. One is logic. Other is power and control. In both cases, replacing the power board (the one that gets plugged into) fixed the AC compressor clutch not activating issue.
 
jsukey said:
We'll have to wait now. Just went out there to throw a test light on it, and everything is working again.
Click to expand...



You know what I'm getting at correct? I don't trust climate controls with circuit boards and temp sensors.

Your pressure switch on the AC line is only 2 wires, correct?


Sent from my iPhone using Tapatalk
 
jsukey said:
I get what you're saying. Yes, the high/low psi switch only has 2 wires.
Click to expand...



If you jump those two wires and your compressor clutch doesn't engage ignore the TX valve, gauge readings and figure out what's going on with the controls.

Your high side should read 100psi plus the ambient psi equivalent of 134a for your outside temp. Mr Durk posted a reading chart for temps and what you should read. Humidity screws up the readings as well as a cooling fan that doesn't operate properly.


Sent from my iPhone using Tapatalk
 
You must log in or register to reply here.

Members online

Total: 1,224 (members: 1, guests: 1,223)

Forum statistics

Threads
278,312
Messages
3,554,085
Members
248,016
Latest member
Advally Service

Share this page

Trending content

Back
Top