Another Ford Ranger AC Issue

[Autosaver]

Before I post the readings, as per request, here are some photos showing:

1. The condenser outlet junction that branches into two pipes
2. The black insulation tape placed on the condenser I/O from which temp readings were taken

[Autosaver]

A digital thermometer was used to measure vent temp on the passengers side - the side that is not/least affected by the mixing of heater core air due to a faulty blend door/flap

FIRST TEST:
1. Drove the car from work to home @ 6pm with 'Max AC' setting on
2. Vent temp dropped to 11C, 4 minutes into the drive
3. Engine temp was cool (electronic display & the line was on C at this time)
4. I noticed that when I braked & slowed down, almost idling, the vent temp shot up to 18C
5. Kept driving & it dropped to 12C but then again when I slowed down, almost idling, the vent went up to 20C in less than a few seconds
6. The vent temp dropped again and hovered between 12-13C during the rest of the drive home

SECOND TEST:
1. Pressed 'Max AC' setting - maximum blower fan speed, lowest temp setting & recirculation setting on
2. Opened all four doors
3. Time was 6.15pm, ambient temp 27C (28C measured) & 89% humidity as per online weather report
4. Engine idling
5. Vent temp was 16.6C, low side 60psi, high side 340psi
6. Condenser inlet 61C, condenser outlet 43C, AC compressor body 68C

THIRD TEST:
1. Pressed 'Max AC' setting - maximum blower fan speed, lowest temp setting & recirculation setting on
2. Opened all four doors
3. Ambient temp 27C (28C measured) & 89% humidity as per online weather report
4. Engine revved & held @ 1500rpm for 30 seconds
5. Low side dropped to 45psi, high side dropped to 310psi. Both low & high pressures held for 25 seconds
6. Condenser inlet & outlet temp...I can't accurately remember!! But they were around 40-43C & 58-60C
7. Didn't manage to get a vent temp reading but I think it got colder
8. What did happen next was what I was looking for. As soon as the engine was allowed to idle the high side shot up to 400psi in about 5-10 seconds
9. Vent temp went to 17-18C
10. Condenser inlet & outlet temp increased to 70C & 50C
11. I put my hand behind the fan & air flow was weak so I put a thick piece of cardboard in the fan blades & the fan slowed down some but it did not stop
12. NOTE: I forcefully rotated the fan first thing in the morning when the engine was cool/cold & there was a lot of resistance. Less than a 1/4 turn
13. After letting the engine idle for a few minutes the readings went back to initial
Condenser I/O = 43C & 65C
Vent temp = 16C
Low & high side = 60psi & 340psi
AC compressor temp = 68C

I was asked if there was any work carried out prior to the AC issue happening - about a year & a half ago the injector pump & injectors were replaced. No modifications have been carried out to the turbo system.

[tbirdtbird]

Thank you for the better pix of the piping.
Well one thing for certain, the comp is OK since it can produce a pressure of 400.
Your pipe I/O to the condenser is 141F in and 107F out for our USA readers. That is about the 30F drop we seek. BUT the pipe in should be considerably hotter, to the point that you can barely touch it. So I am still not sure if your readings are accurate.
Your pressures are obviously still too high.
Have to wonder did the AC performance suffer a very rapid crash or did it come on slowly.

Having said all this, please be aware that the behavior you are seeing at idle, ie pressures and temp rise, is totally normal for any mobile AC.
A comp does very little work below an engine RPM of 1500, thus we ask for data at that speed.

We need to get input from JohnHere, but I do think you have reheating at the very least. But that is insufficient to account for the high pressures you are seeing, unless this vehicle is also overcharged, as so many are.
So many times on here it has been said by the pros that in order to determine where your problems exist in mobile AC, that you must first make very certain that the system has the correct charge. I am leaning toward recovery, evacuation, and recharge to underhood sticker spec as the next step.

[Autosaver]

What do you mean by re-heating problem?

Also I hooked up the scan tool last night & noticed that the evaporator temp reading was 26C when the vent temp was 12C. I understand that if the sensor was faulty & gave a reading of -12C (like I have seen in a Nissan Juke) then the AC compressor will cycle on & off because it thinks the evaporator is freezing. Back to the Ford Ranger, I'm not too sure if the evaporator temp reading is inaccurate because of the scan tool software (I used a G-Scan 2), the sensor is bad OR there is another issue behind the dashboard (heater core air mixing into evaporator core but then vent temp is cold).

I'll recover, vacuum & refill today.

[tbirdtbird]

"heater core air mixing into evaporator core air"

this is what we call re-heating. If your AC vent temps are better when the car is first started (remember to test at 1500 RPM) than when the engine is hot, you have re-heating taking place

More common than you might think

[Autosaver]

Do you think that the heater core heat is being absorbed into the evaporator core & causing the pressures in the system to rise?

I also did a quick test this morning when things were pretty cool:

1. Low & high: 50psi & 300psi (started at 48psi & 260psi)
2. I didn't measure vent temp but it was cool-cold
3. Revved the engine for 5 seconds
4. After revving the engine the high side pressure started increasing to 400psi & felt the vent air with my hand - slight temp increase
5. Confirmed during the first 5 minutes of driving to work that the AC was cold & then went warm when I slowed down. Then went cold again when I sped up & cruised @ 50-55km/h

[tbirdtbird]

"Do you think that the heater core heat is being absorbed into the evaporator core & causing the pressures in the system to rise?"
No. reheating means that (typically) a diverter door has failed and allows the fan to blow air over both cores, thus reheating the air that the evap already cooled off.

" I didn't measure vent temp but it was cool-cold"
What does this mean? We need temps. If y'all are gonna do AC work you really need a vent thermometer, they are cheap

I thought you were gonna block off the heater hoses? On some cars, tho, doing this permanently can allegedly create a problem (I can't for the life of me understand how this could be). But for temporary testing purposes, it is OK.

Your pressures are still too high

[Autosaver]

Noted.

I do have a digital thermometer but was in a hurry to get on the road so I skipped vent temp measurements.

Yes I removed the heater core hoses & joined them:
1. Both passenger & driver side vents now read 6C @ idle but low & high side @ 50psi & 350psi (too high)
2. Took the car for a spin & vent temperature got as low as 3C when car was cruising @ 40-45km/h
3. Accelerated & held engine rpm to 1500rpm for a few seconds & then pulled over to let the car idle. Vent temp went up to 8C & then I heard the compressor turn off & vent temp jumped to 12C (HPCO working because of excessive high side pressure). After a few seconds the compressor turned back on & vent temp gradually dropped to 7C.
4. Ambient temp during the above tests was 30C & 79% humidity

As you & John mentioned, pressures are too high so I am going to now recover, vacuum & refill according to spec.

[tbirdtbird]

OK, please remember that pressures and vent temps at idle are meaningless.
If the heater hoses are connected together then at this point you cannot have reheating

[Autosaver]

In the end the owner of the car requested their car for use over the weekend. I'm going to get it back from them & then I'll recover & recharge to spec.

All I could really do was connect the gauges & release a little bit of gas which took the high side pressure from 300psi to 280psi (car had been sitting outside in hot sun). Don't ask where I released the gas into - just know that where I live there are no laws condemning improper release of R134a.

While driving the car back to the customer, vent temp dropped to 11C & then I had the same issue again where I would slow down & the vent temp shot up to 18C (engine not @ operating temp). I'm really leaning towards an intermittent fan issue so I'm going to search up any TSB's for the fan clutch. I also mentioned that there was at one time a cold spot on the top right area of the condenser so could it be possible that there is also a blockage? That being said, condenser I/O temp readings were good & the AC has days where it's perfect (according to vent temp) where it stay cold the whole time.

Referring to an earlier post, after the heater hoses were joined & the car was test driven - the vent temps dropped as low a 3C & were equal across all four vents. When I dropped the customers car back to them later during the day, there was now a vent temp difference between passenger & drivers side of 4C. Before the heater hoses were pulled the vent temp difference was 6-8C. This Ford Ranger does not have a button setting which allows fresh air from the outside to be allowed into the cabin. As far as I'm aware there is only recirculation mode - so where is this additional heat, causing the vent temp difference, coming from?