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Jeff NJ's Avatar
 
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AC suddenly warm

Took the car to work today and of course its like 95 here, so I turn on the AC and it blows warm air.

It worked fine last week and haven't touched anything. I checked the red relay by swapping it with another one and its not that. I checked the connectors to the compressor and they are good. When I turn on the AC, the compressor does not kick on, and the RPMS don't drop at all.

So what else can cause the compressor to not kick on?

I have a Griffiths system with the center vent and his evaporator, new barrier hoses and his condensers, but the compressor is original.

thanks!
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Old 07-20-2017, 01:05 PM
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Hey Jeff,

Griff's system probably means you have a high-side, high/low pressure switch, so if the refrigerant pressure is too low (if there is a leak somewhere that allowed refrigerant out), the switch will block current to the compressor clutch.

Find the switch and then jumper it (probably close to the high-side port on the compressor) - if clutch comes on, then you know that it is either a bad switch or low charge level . . . can't really tell which without putting gauges on the system.

If clutch doesn't engage, unhook the lead to it and test for current there (whatever your running voltage is), with switch still jumpered and then with switch hooked up as normal. If there is current there, then you know that there is a problem with the clutch (not likely, however).

Don't drive around with switch bypassed, as low charge running will damage the compressor, but not a problem for brief testing purposes.


When you say "red relay", are you referring to the one in the smuggler's box (probably not, as those aren't red). If that relay eff's up, the clutch won't engage (no power to it), butt usually the evaporator blower won't run,either. Butt regardless, find that relay, and tap on the case with a screwdriver handle, etc. - if the points inside are stuck, then tapping might free them up. If it does, then you can open the relay and clean the points, or buy a new one.

Last edited by Rawknees'Turbo; 07-20-2017 at 01:51 PM..
Old 07-20-2017, 01:49 PM
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Thanks Ronnie,

the red relay is on the fuse panel in the frunk. Round and red. Its labeled AC on the fuse panel schematic. I swapped it with another red relay to no avail.

Is this the pressure switch blocked out in red in the pic below? Assuming so, I disconnected the two leads and bypassed the switch so the two wires from the car (one from the wiring harness and one to the compressor are connected now.)
Tried it and still nothing, so it seems like the switch is not the culprit.

Evap blower is running since I definitely get air from the Griffiths center vents when I turn on the AC.

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Old 07-20-2017, 02:11 PM
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D'oh!

Scratch that.

Turns out you have to actually TURN ON the AC when testing the compressor with the switch bypassed. LOL

So when I tested it with the AC on, the clutch engaged.

So now I need to figure out if the switch is bad or I have lost pressure...
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Old 07-20-2017, 02:17 PM
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Yes - that's the pressure switch.

Test the switch for continuity with your multimeter (should have continuity between the pins if contact point inside is closed - no continuity means open due to bad switch or low charge.

Test for current at switch sockets - with engine running and a/c thermostat and fan on high. If no current, check smuggler's box relay and look to see if there has also been a fuse added somewhere (like near relay).
Old 07-20-2017, 02:19 PM
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Ok, I don't know how to actually test the switch with it installed (can test on bench, but that means removing it and letting refrigerant out).

If you borrow some gauges from Autozone, I will walk you through how to test your system pressures to see if charge is low.
Old 07-20-2017, 02:21 PM
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If you borrow gauges, it would also be a good idea to borrow a vac pump so you can remove air from gauge set and it won't enter you system.
Old 07-20-2017, 02:23 PM
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As a simple test, if I bypass the switch and let it run for a minute, it should get cold, no? If it does, then I have at least some refrigerant, but if it stays warm, that would tell me I have lost my refrigerant.

Correct?

How long can I safely run it without the switch? Is 60 seconds too long?? That would be enough time to get cold air, I would think.
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Old 07-20-2017, 02:25 PM
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Jeff, is there a lot of oily residue in the area of the backside of the clutch, and maybe flung on the underside of the engine lid? if so, that would mean that the compressor nose/shaft () seal is leaking.
Old 07-20-2017, 02:29 PM
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No problem running it for several minutes with low charge.

Yes to what you said - those switchs' low cutoff points are very low - meaning you would have little to no cooling if pressure low enough to trip switch.
Old 07-20-2017, 02:30 PM
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Tried it. Warm air... Bumming

All around the clutch is dry, so I don't think the seal is leaking.

I noticed that the actual pressure switch easily rotated on the threads. I turned it a quarter turn to tighten it by hand. Here is a pic of the tin right below the switch. Its definitely wet, but could be oil too...

It doesn't seem like enough is there though if this is the leak. Does it evaporate?

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Old 07-20-2017, 03:07 PM
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The pressure switch being loose like that means that it was leaking. There is probably an o'ring that sits in the groove of the boss/fitting that the switch screws into (). You will want to get a new o-ring - can be found at most any auto parts store, but NAPA for sure (at least the one by me has a huge assortment) - get the green colored one.

Lightly lube new o-ring (I like to use silicone grease - other people insist on compressor oil) and snug the switch down - watching to make sure that the o-ring seats and does not get pinched (maybe get a couple of the o-rings in case one gets damaged - easy to do).

That is likely a little bit of a/c oil that you see on the engine tin - not enough to be concerned with adding any new oil to your a/c system. The refrigerant gas evaporates as it leaks.

If you want to try servicing the system yourself, with loaner tools from Autozone (like Deez did), I will be glad to help (plus you have that novel on a/c vac and charge procedures that I put in Deez's thread ).

Last edited by Rawknees'Turbo; 07-20-2017 at 03:32 PM..
Old 07-20-2017, 03:30 PM
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I'm 90% into the same problem/fix as Jeff. Griffith's with 3x Condensers [1x Decklid and 2x in Rear Fender] and all the Griffiths extras: Evaporator, Fan, Hoses, Switches, etc... It has worked great for 4+ years. However, last month, I noticed it was not cooling as well. After much searching, I determined there was a very small leak at the decklid condenser and hose connection from the compressor - Same hose as Jeff's just the leak was a few feet down the line...

I changed out all my O-rings and purchased a new dryer from Griffiths. Pressure tested with Nitrogen @ 150psi for 2-days - - No leaks. So, pulled a vacuum and just had a tank of 134A dropped off so I'll fill it this weekend.

Moral of the story: a small leak will cause the same issue Jeff is having... Hope you get it resolved! Shannon
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Old 07-20-2017, 04:06 PM
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Lots of real good info already.

Before charging it unscrew the lines just a little at the manifold and maybe even the fittings so R134 or whatever you're using will purge the air out of the lines.
Expecially the yellow hose. It's threads may have a groove in them just for purging any air out of the line before charging.
Old 07-20-2017, 06:09 PM
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Quote:
Originally Posted by mooney265 View Post

Moral of the story: a small leak will cause the same issue Jeff is having... Hope you get it resolved! Shannon

Yup. I have a low side schrader valve leaking. I just topped off the system. I'll check everything and fix any other leaks over the winter.



Sent from my iPhone while Driving
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Old 07-22-2017, 07:35 AM
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Quote:
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Lots of real good info already.

Before charging it unscrew the lines just a little at the manifold and maybe even the fittings so R134 or whatever you're using will purge the air out of the lines.
Expecially the yellow hose. It's threads may have a groove in them just for purging any air out of the line before charging.
With my manifold setup, I can use the vacuum pump to draw down all of the lines right up to the quick connectors and to the 30lb bottle of r134. This may not be possible with the various manifold setups and their configurations, but take a look at yours and see if it's possible.

On edit- Jeff I see you're in NNJ- you're welcome to borrow my rig. I'm in 10598
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Last edited by gsxrken; 07-22-2017 at 08:50 AM.. Reason: Adding
Old 07-22-2017, 08:44 AM
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Wow, that's super nice to offer Ken. I just googled it and its a 90 minute drive to your zip from my house. I'll see if the local auto parts store offers it, but if not, Ill let you know. Thanks!
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Old 07-22-2017, 10:03 AM
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Quote:
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Wow, that's super nice to offer Ken. I just googled it and its a 90 minute drive to your zip from my house. I'll see if the local auto parts store offers it, but if not, Ill let you know. Thanks!
Jeff, I would take Ken up on his offer - his gear () is better than what the loaner tools will be, he has a 30lb pound cylinder of r134a that he would likely "sell" you the amount you need (using 30lb tank is way better than multiple, small cans . . . not THOSE cans), and you'll be able to get some tips (not THAT tip) from him in person.
Old 07-22-2017, 10:13 AM
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With my manifold setup, I can use the vacuum pump to draw down all of the lines right up to the quick connectors and to the 30lb bottle of r134. This may not be possible with the various manifold setups and their configurations, but take a look at yours and see if it's possible.

On edit- Jeff I see you're in NNJ- you're welcome to borrow my rig. I'm in 10598
I have Mastercool USA made manifold gauges. I can draw a vacuum throughout the entire thing and all 3 hoses but you never get 100% of the air out.. it's impossible while you're on earth.

By purging all the lines and the brass manifold everything is screwed into you have them 100% filled with AC refrigerant and nothing else. This way nothing is going into the AC system other than refrigerant and refrigerant oil if you're adding any oil.

When I do an AC charge I do a 3 hour evacuation with a high quality Robinaire two stage vacuum pump. It's amazing the electric motor on it even says made in USA!

Then I let it sit overnight with the gauges and hoses still attached. Then check it next day and if it's still holding a vacuum I run the vacuum pump another 3 hours. Probably more than needed but there is over 40 feet of AC hose in a 911 and the receiver drier, front condenser, and evaporator with expansion valve are around 20 feet of hose away from the compressor so it can take a while for all the moisture to boil out of those places and make it's way to the shrader valve on the compressor while nothing is moving through the hoses.

After getting it all charged as good as you can you can still improve how cold the AC vent temps gets by "sweeping" the system. Do that after it's fully charged and has run a little by slowly loosening a hose fitting from the front condensor and let the refrigerant leak out.
Let it out slowly so you don't blow much oil out with it. Then tighten the fitting when regrigerant almost stops coming out. By doing this any moisture that was still in the system mixed in with the refrigerant got blown out with the refrigerant while it was leaking out and pressure was equalizing.

Then evacuate it again as said before and charge it again. Doing this might make vent temps a little colder if there were any remnants of air and moisture still in the system.
Good luck with it.
Old 07-22-2017, 10:44 AM
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So I charged the system yesterday [98F outside] and was able to get the High Side pressures up to the recommended 265psi. The system was working great with a 30F temp drop across the evaporator with the fan on med speed.

The problem, however, is my leak came back. Unfortunately, my pressure test of 150psi of Nitrogen was not enough to fully check the system. My reading said that doing more than 150psi for the 'system' could possibly damage the expansion valve or the evaporator as they normally don't see that type of pressure.

In the wake of my findings, I reached out to Charlie [at Griffiths] and he said I could have pressure tested the nitrogen to 275psi and not risked any harm to the cold side of the system. While the leak is very very small, I cannot stand for it and will be evacuating the system and sending some pictures of the hose and the condenser where the leak is occurring.

I've attached a picture of the temps I was getting [dual probe] on the car mat and the front vent. Mind you, it was 98F outside yesterday. That's a 40F drop... That's what 3-condensers gets you...

Shannon


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Old 07-22-2017, 04:42 PM
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