AC compressor shuts off after 3 seconds (1 Viewer)

[JOMZSHAKES]

I'm starting the diag process for this and could use some wisdom to narrow down my tests.

1998 100 series LC

AC compressor turns on every 12-15 seconds, and turns off after 3-5 seconds of running.

I've checked the low side and it's 30-40psi

I'm wondering what's possible because the relay is clicking on and off, AC dash light stays on, and when it's cold it's cold.

Since the car has 360k miles I'm willing to throw some cheap parts at the problem like a AC relay. Which one is the AC relay?

I've read some stuff on AC clutch gap, my clutch gap is .269 inches. It shows online it's supposed to be .014-.026 inches. mine does kinda look like it's poking out and I did just have all the belts off.

How do I tighten it?

 

[JOMZSHAKES]

Also I measured from the pulley to the "bell cap?" Not sure what to call the most outside mart I think it's a clutch cover. Is that what I need to measure?

 

[vipergrhd]

You said it gets cold, did you measure how cold it gets? 30-40 PSI is that static or dynamic pressures? You can swap the relay if you like just to eliminate that issue and clutch gap is not an issue at all the magnet will pull it even when it's out of specs. Did you try adding from freon?

 

[JOMZSHAKES]

feels like "ACC" relay is air conditioning compressor.

 

[JOMZSHAKES]

yes i added r134a to the low pressure side, i only tested it with the dumb gauge on the autozone can. does it use freon and i used the wrong refrigerant?

im guessing the compressor wasnt on when adding the refrigerant because it stays off most of the time so i could have done that wrong too, seemed to work really quick now that i thiunk of it.

i have no clue what static or dynamic pressures are and i dont own a manifold or anything, just doin my best out here.
are you guessing its shutting off because of refrigerant leak somewhere?

 

[TenderTendon]

Sounds like your system is short cycling due to a low charge (likely caused by a leak). Your low side should never get below 40 psi, because at approximately 38psi, the low pressure safety cutoff switch will turn on and releases the clutch until the pressure rises above set pressure. This cycle will continue until the system has enough charge to keep the low side above ~40psi. Add a can of 134a and you will see the cycling stop. Then you can start searching for the leak.

 

[JOMZSHAKES]

swapped relays, and no change in behavior

 

[JOMZSHAKES]

Added refrigerant, almost instantly it went from 40 to halfway in the red.
Then it made a crazy buzzing noise twice, 15 seconds apart, and I turned the AC off and it stopped. I'm kinda scared now

 

[JOMZSHAKES]

I'm about to shove a screwdriver in there and release some pressure while I hold my breath

 

[vipergrhd]

That is odd, is it possible for you to video while it's happening? I cannot trust those gauges that come with the can better invest in a gauge set. My hunch is you may have blockage in the system or a bad expansion valve that is just a guess for now since we don't know what your high side is reading when all of this is happening.

 

[JOMZSHAKES]

I just put the can hose end onto low pressure "near firewall", and after hitting the trigger for like 2-3 seconds it went into the red

 

[JOMZSHAKES]

I can hear the valve engaging and opening when I put it on, I released some pressure and it's still in the red, it seemed like a lot of pressure

 

[Moparsncruisers]

Sounds like low refrigerant, you need to go somewhere and have it evacuated and recharged..that's the only way to know your current charge level.

 

[JOMZSHAKES]

yup, gonna go to my AC guy and get a vacuum recharge and add dye and take it from there, any common leak points?

 

[Brandon Ryder]

yup, gonna go to my AC guy and get a vacuum recharge and add dye and take it from there, any common leak points?

Expansion valves in front and rear, evaps in front and rear, the hard lines on the passenger side wheel well tend to get damaged from road grime. If you have corrosion, you could have a corroded line near any of the hard line brackets that go to the rear a/c.

 

[TenderTendon]

Sounds like you got liquid in the pump when adding the refrigerant. Make sure the can is upright when filling, not laying down or upside down. Also, keep the motor at ~1500 rpms with A/C on max cool.

 

[vipergrhd]

yup, gonna go to my AC guy and get a vacuum recharge and add dye and take it from there, any common leak points?

Great idea! Let the mechanic deal with it as long you trust the shop, if possible ask how much freon/refrigerant they pulled and have them add at least 1 ounce of oil back in the system.

 

[leveeguy]

And also be sure to run the rear a/c while adding freon also.
Whatever you do don't run rear A/C while adding freon, per Moparsncruisers

 

[Moparsncruisers]

And also be sure to run the rear a/c while adding freon also.

Makes zero difference when charging

 

[Moparsncruisers]

yup, gonna go to my AC guy and get a vacuum recharge and add dye and take it from there, any common leak points?

With the age on these could be from anywhere, like the other guy said ask how much was evacuated. Unless the leak is obvious let the system run with the dye in it for a few weeks then try and find it with a UV light. Small leaks can be tricky and take time to find, be patient and enjoy the AC until it blows warm again!