Need some direction....

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Fhlferg
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Joined: Tue Jul 18, 2017 5:07 pm

Need some direction....

Postby Fhlferg » Tue Jul 18, 2017 5:22 pm

99 Ford F250 super duty V10 Gas

AC has progressively got to the point where it doesn't cool at idle, but cools some when driving. (But still not like it used to)

Ambient temp today 94

Center vent temp at idle was 74
Center vent temp @1800 rpm when parked 66

Pressure Readings at idle:
Low - 75psi
High- 320psi

Pressure at 1800 rpm when parked:
Low- 65
High- 425

Compressor clutch was spinning the whole time and never shut off until i unplugged the low pressure switch. Then when i plugged it back in, the clutch was spinning again.

Cooling fan was turning appropriately. No notable deffects in coil and it was not dirty to speak of.

I did notice a rattling type sound when the compressor was running that disappeared when i turned the system off.

I added some freon with uv dye yesterday. It cooled better at first, but went back to its current condition pretty quick. Waiting for the sun to go down a little before i look for uv dye leak.

What should I look at next? Or am i looking at a weak compressor?

Thank you
Craig
Fhlferg
Posts: 9
Joined: Tue Jul 18, 2017 5:07 pm

Re: Need some direction....

Postby Fhlferg » Tue Jul 18, 2017 6:11 pm

Additionally, this was first really evident about 2 weeks ago. I don't recall all of the temps and pressures at that time, but the low side pressure was 45 with an ambient temp of 97.

https://photos.app.goo.gl/bdECHfq0TS80NMYs2

So using this chart i added freon and got the liw side up to about 55psi. It cooled better for a day or 2 but then back where we started. So i figured there was a leak some where.

Went out of town for a week and when i for back yesterday is when i added the freon with uv dye. They didn't have just the dye locally so i used the combo without checking the pressures again.


But then today, i got the pressures in my original post. Headed out to check for a leak momentarily.
Last edited by Fhlferg on Tue Jul 18, 2017 7:06 pm, edited 1 time in total.
Fhlferg
Posts: 9
Joined: Tue Jul 18, 2017 5:07 pm

Re: Need some direction....

Postby Fhlferg » Tue Jul 18, 2017 6:27 pm

Just checked for uv leak.

Only thing i could find was a light haze of the green around the compressor clutch. The circular part of it, not the triangular plate, but just behind it.

You can see it in this photo link: https://photos.app.goo.gl/jZRDILQuZcLkPXDH2

Also visible between clutch and compressor here:
https://photos.app.goo.gl/Ji9toRnTih6oHVPd2

So am i looking at a bad compressor and clutch assembly?

I also noticed that there is a motor oil leak and the compressor and surrounding area have a lot of motor oil residue. Would this be the root cause of the compressor to fail?
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Cusser
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Joined: Sun Apr 24, 2016 6:29 am

Re: Need some direction....

Postby Cusser » Tue Jul 18, 2017 7:56 pm

Oil on the compressor's clutch is not good, but slippage does not appear to be the acute issue, your pressures are. If your fan shroud is intact, I do suspect your fan clutch or electric cooling fans, your condenser seems to be unable to shed its heat. You state the fan is operating; well, if there's a fan clutch on your truck, you need to test that (see Google); I just replaced the fan clutch on my Nissan truck 3 weeks ago (it failed the rolled up newspaper test miserably), and that fix really helped my AC.
Fhlferg
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Joined: Tue Jul 18, 2017 5:07 pm

Re: Need some direction....

Postby Fhlferg » Tue Jul 18, 2017 9:01 pm

Yes, mechanical fan with clutch. Not electric. Thank you for the reply. I'll look into testing the fan clutch.
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bohica2xo
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Location: Las Vegas, NV

Re: Need some direction....

Postby bohica2xo » Tue Jul 18, 2017 9:25 pm

425 psi is a condenser issue, not a weak compressor.

Generally an airflow issue. Condensers clog deep in the fins with small debris & insects. The face can look clean & still be plugged.

Wait for dark. Hang a shop light or bare bulb in the radiator shroud, and start looking straight through the heat exchanger stack.

You can clean a cold condenser face with a strong surfactant like Simple Green or similar. Spray it straight in to the fins as deep as you can & let it soak for 5 to 10 minutes. Then hose it out with a garden hose. Do NOT use a high pressure washer - it will bend fins. Garden hose pressure & plenty of volume.

Repeat if you see a lot of crud hit the ground. Surfactants dissolve gnats, flies etc. as well as oil & dirt.

See it less here now that the gnats along the Colorado river have been controlled. Rural vehicles more often.

Make sure all of the OEM shrouds & air dams are still in place too.
Fhlferg
Posts: 9
Joined: Tue Jul 18, 2017 5:07 pm

Re: Need some direction....

Postby Fhlferg » Wed Jul 19, 2017 6:52 pm

bohica2xo wrote:425 psi is a condenser issue, not a weak compressor.

Generally an airflow issue. Condensers clog deep in the fins with small debris & insects. The face can look clean & still be plugged.

Wait for dark. Hang a shop light or bare bulb in the radiator shroud, and start looking straight through the heat exchanger stack.

You can clean a cold condenser face with a strong surfactant like Simple Green or similar. Spray it straight in to the fins as deep as you can & let it soak for 5 to 10 minutes. Then hose it out with a garden hose. Do NOT use a high pressure washer - it will bend fins. Garden hose pressure & plenty of volume.

Repeat if you see a lot of crud hit the ground. Surfactants dissolve gnats, flies etc. as well as oil & dirt.

See it less here now that the gnats along the Colorado river have been controlled. Rural vehicles more often.

Make sure all of the OEM shrouds & air dams are still in place too.



Thanks for the info. I was also concerned that I may have over charged it which may be giving me the higher pressures?


I will look at cleaning the condenser and see what that does as well.

Thanks again,
Craig
Fhlferg
Posts: 9
Joined: Tue Jul 18, 2017 5:07 pm

Re: Need some direction....

Postby Fhlferg » Wed Jul 19, 2017 8:41 pm

Checked cooling fan clutch- doesn't appear to be any issues there. Spins appropriately before having started the truck, spins appropriately compared to motor rpm, doing a "newspaper test" didn't even try to slow it down.


Looking at the condenser it's wasnt particarly dirty. But i cleaned it anyway. I'll recheck cooling efficiency, vent temps and pressures during the heat of the day tomorrow.
I will say there is quite a bit of impact damage from bugs rocks etc, visible on the fins. But it's been like that since i bought it 3 years ago. It doesn't look Amy worse than it has, but if i were to put a number to it I'd say 40% of the total condenser surface shows impact marks. That's not a 40% total occlusion, just 40% has impact marks. If that makes since.


What about the uv dye residue I'm seeing around the compressor near it's clutch? The noise I'm hearing under the hood is definitely coming from compressor when it's running and sounds like a ball from a bearing rattling around.
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bohica2xo
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Location: Las Vegas, NV

Re: Need some direction....

Postby bohica2xo » Thu Jul 20, 2017 9:07 am

An overcharge of oil or refrigerant can cause high head pressures.

Your original post mentions a slow decline, which absent adding anything to the system is usually a condenser problem.

If you have added materials to the system and then it changed, that is a different condition.

.
Fhlferg
Posts: 9
Joined: Tue Jul 18, 2017 5:07 pm

Re: Need some direction....

Postby Fhlferg » Thu Jul 20, 2017 8:07 pm

Bohica2xo

Yes I understand. I tried to lay that out in the posts just after the original. It dawned on me after the original post that it would be relevant information.

How do you think i should proceed?
Evacuate the system, pull a vacuum and recharge to oe spec, then test?

With the uv dye residue im seeing at compressor clutch, I'm thinking i need a new compressor because of a leak. Or is that more of a sumptom of overcharging?

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