Ford Ranger Compressor Cutting Out

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tbirdtbird
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Re: Ford Ranger Compressor Cutting Out

Post by tbirdtbird »

"So if I used an infrared thermometer I'd be looking for the temperature difference between the condenser inlet & outlet?"

Of course. The job of the condenser is to give up the heat that was absorbed from the cabin! It changes the hot vapor state 134 back to liquid 134 (ie condenses the vapor) to start the cycle all over again.
This value does not depend on the specific car. There should be at least a 25F temp drop, 30F is better. All coils no matter the application, should be able to produce a 30F temp drop. The outdoor unit (coil) for your home AC will have a 30F drop across it.

You want to learn AC? Do both tests.

There are many overcharged AC systems out there simply because most 'technicians' equate poor AC performance with the system being low on refrigerant. ie they are not capable of a proper diagnosis. See it all the time, even on residential. I do both MVAC and residential. I believe JohnHere does also.
When considering your next auto A/C purchase, please consider the site that supports you: www.ACKits.com
Autosaver
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Re: Ford Ranger Compressor Cutting Out

Post by Autosaver »

Just an update...

TX valve & condenser dryer filter were replaced (parts order was placed well in advance of me posting this thread). System was vacuumed & refilled with the correct amount of r134a.

The high side pressure sat way lower than the initially observed 300psi - 210 to 220 psi to be exact. Low side at 45 to 50 psi.

Had someone rev & hold the engine > 1500 rpm & the high side only went as far as 250 psi. During the initial inspection the high side pressure started at 300 psi & increased to 400 psi, when revved & held > 1500 rpm, which then caused the compressor to cut out.

Because the high side slowly climbed to 250 psi I'm thinking I should've also replaced the condenser. That being said I did a general 'feel' test the first time & the outlet was cooler than the inlet. Whether I might also have a blockage in one of the tubes? I don't know, I didn't have an infrared thermometer to go across the condenser tubes at that time.

Took the car for a 30-40 minute test drive, up hill, to keep the engine at it's warmest & rpm high. The AC stayed cold throughout the test drive. Thermometer vent readings dropped as low 1 degrees C - mind you it was a cool overcast day today (ambient temp ~ 29 degrees, ~ 25 degrees C at the higher end of the hill)

Anyways I got a hold of the old TX valve & held a heat gun to the sensing side. When heated, the valve did not move. Just wondering if this is a valid bench test for a TX valve?
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Cusser
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Re: Ford Ranger Compressor Cutting Out

Post by Cusser »

Autosaver wrote: Fri Sep 30, 2022 12:35 am Took the car for a 30-40 minute test drive, up hill, to keep the engine at it's warmest & rpm high. The AC stayed cold throughout the test drive. Thermometer vent readings dropped as low 1 degrees C - mind you it was a cool overcast day today (ambient temp ~ 29 degrees, ~ 25 degrees C at the higher end of the hill)
I think you're close; I'd replace the fan clutch.
tbirdtbird
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Re: Ford Ranger Compressor Cutting Out

Post by tbirdtbird »

Agree.

The condenser outlet should be cooler than the inlet. Too bad you don't have an IR temp gun. Ya wanna work on AC? Ya gotta have some tools.
1°C is about 33°F which is a mere one degree above freezing. You don't want to be at freezing, else the evap will freeze and turn into a solid block of ice.
Your ambient is 84 degrees F, which is a decent temp to be testing at.
As of now, a hi side of 250 is acceptable.
I myself would NOT replace the condenser.

Re-read what Cusser wrote....you are nearly there. You were overcharged. A very very common problem. Most people and 'technicians' have no idea how to properly diagnose, and they just shove more refrigerant into a poorly performing system willy-nilly.
When considering your next auto A/C purchase, please consider the site that supports you: www.ACKits.com
tbirdtbird
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Re: Ford Ranger Compressor Cutting Out

Post by tbirdtbird »

"Anyways I got a hold of the old TX valve & held a heat gun to the sensing side. When heated, the valve did not move. Just wondering if this is a valid bench test for a TX valve?"

At room (ambient) temp the valve should already be open, adding a source of external heat will not make it open any more.
The correct way to test a TXV is to get a can of computer dusting air (which is actually R152), and invert it, and spray the ice cold spray onto the TXV bulb, the valve should close, and then reopen when it warms back up.
An inverted can will allow liquid refrigerant to exit the can, where it will flash, and frost up anything in its path. Perfect solution for cold testing.

As we said in the beginning the problem was not your TXV. All that was needed was a proper evacuation and a proper recharge. Glad you got it working, tho.
When considering your next auto A/C purchase, please consider the site that supports you: www.ACKits.com
Autosaver
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Re: Ford Ranger Compressor Cutting Out

Post by Autosaver »

tbirdtbird wrote: Fri Sep 30, 2022 7:26 am You were overcharged. A very very common problem
1. I'm also thinking that. I should've asked them if they had refilled it prior to coming to the shop however they did not say that they had OR tried to refill the AC themselves. I know the person well & they don't really take their car anywhere else so I just assumed I was looking at an untouched system.
2. At least I know now that the 300psi high pressure readings I was seeing on two other previous Fords that came through were not standard. One of them was refilled after replacing a compressor. Like you said most likely the other technician overfilled the system OR there was another underlying issue that was not picked up.
Autosaver
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Re: Ford Ranger Compressor Cutting Out

Post by Autosaver »

Tbirdtbird, I started using this chart (see attachment) as reference for gauge pressures...what do you think?
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tbirdtbird
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Re: Ford Ranger Compressor Cutting Out

Post by tbirdtbird »

I would sideline that chart. The lo side numbers are way too high for the higher ambient temps and would result in very little cooling. Regardless of all other factors, we like to see a lo side about 30-35, certainly never over 40 regardless of ambient. And this is Texas, think we see high ambients...
Recall that your lo side psi is nearly equal to the temp at the evap. You lose 5 degrees of cooling (ie a rise in vent temp of 5 degrees) from the moment the air rushes past the evap fins and splashes out of the vent. So a lo of 40 psi equates to a coil temp of about 40F and thus a vent temp of about 45F. If you can hit 45F at the vents you have done your job.
So from the chart at 100F ambient, the low could be 55 psi, so the vent temp will be 60F. I doubt anyone would consider that to be actual air conditioning. Cheaper to just open the windows.
In this state I have never seen a properly working auto AC system blow less than 45F, usually more like 40F, no matter the ambient.

As a general rule of thumb, for the hi side, the ambient x 2.2 plus 20% should be about where you want to be. The high side is most definitely keyed into the ambient, way more than the low side.

Some experts here say the high is acceptable if the high is as much as ambient x 2.5 plus 20%. But I would not go over that without looking for a condensing issue or a charge issue.

Here in our shop, we never want to see a high greater than 275
When considering your next auto A/C purchase, please consider the site that supports you: www.ACKits.com
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JohnHere
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Re: Ford Ranger Compressor Cutting Out

Post by JohnHere »

tbirdtbird wrote: Fri Sep 30, 2022 5:00 pm I would sideline that chart.
I agree with the cogent explanation already given. Strive toward getting the low-side pressure into the range it's supposed to be in and forget the chart.
Member – MACS (Mobile Air Climate Systems Association)

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Autosaver
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Re: Ford Ranger Compressor Cutting Out

Post by Autosaver »

Thanks John & Tbird.
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