Another Ford Ranger AC Issue

[tbirdtbird]

It will be hard to answer any more questions until we have the correct charge on board, only then can the AC function at its maximum. In the meantime, all bets are off. You are putting the cart before the horse.

[JohnHere]

As a first step, I recommend the same as the comment immediately above.

To my way of thinking, this 2017 model-year truck is still relatively new. But that's not to infer that the refrigerant charge and oil amount are correct. I don't believe we know the repair history (if any) of this system, either. Anything could have been done to it in the past, including adding too much oil and "topping-off" the refrigerant, perhaps grossly overcharging it by someone blissfully ignorant of industry-standard MVAC servicing procedures.

An overcharge of oil or refrigerant, or both, will raise pressures to abnormal levels and compromise cooling.

For now, let's hope (guess) that the oil amount is correct and begin with the obvious: Recover the existing charge; replace the R/D desiccant (kits are available); evacuate for at least a couple of hours down to 500 microns, if possible, depending on the elevation of your locale; and recharge by weight using pure R-134a or R-1234yf (whichever it takes) according to the manufacturer's specifications.

Chemours (DuPont) refrigerants, which are produced in the USA, are known for their purity and high quality. But they might not be available in your country. In any event, I avoid using refrigerants produced in the Asian countries as they often contain unknown refrigerant mixes and harmful additives, such as sealer, which will clog the system and also raise pressures abnormally.

I don't have the refrigerant and oil specs for this vehicle. Hopefully, the under-hood decal that lists them is still in place.

[Autosaver]

Update:

Got the car back in last month & recovered & recharged the system with correct quantity as per Autodata - there is no AC gas charge sticker under the engine bonnet. Also did a few Google searches there is only a 10-20g variation between specifications.

The car has come back in today for general servicing & while the customer hasn't mentioned anything about the AC, I have picked up two issues:

1. When the car is left standing for a while in the sun & then turned on, 'Max AC setting' turned on, the AC is very warm (obviously)
I say this is an issue because we had another Ford Ranger in & under the same conditions the AC went cold relatively quickly
The car has to be driven for a few minutes (> 5 min) until the vent air starts to go cold
2. Most noticeably when the car is left idling, there is a temperature difference between the driver & passenger side vents! BUT the heater hoses
were pulled from the heater core so why does it look like a reheating issue? Styrofoam plugs were also used to block the heater core pipes to ensure hot
air from the engine didn't enter the heater core

I couldn't carry out proper AC testing (time constraints) but I managed to hook the scan tool up to the car & take it for a test drive.
For problem (1) the AC high side pressure is initially about 2850-2950 kPA. When the car is driven the pressure reading drops to about 2450-2550 kPA & AC vent temperature improves.
When I pulled the car over & let the engine idle the pressure reading gradually went up to about 2600-2700 kPA & the AC was still cool to the touch but warmer.
I let the car free roll, in drive, downhill & pressure reading dropped to about 2150-2200 kPA & AC vent temperature was cold.

I think the viscous fan coupling needs to be replaced. My theory is that there is too much slippage in the beginning when engine temperature is cool resulting in poor air flow & therefore poor AC performance. When the car is driven & the engine heats up, the fan coupling is better therefore resulting in better air flow & improved AC performance. That being said I don't think it is good enough to provide the best air flow required.

I really want to install an electric fan conversion kit. Apparently they provide 3-4 times more air flow than the standard OEM fan coupling.

As for problem (2) well I'm stuck on that one - anyone know how else warm air might enter the vent system?

[tbirdtbird]

1. Viscous fan couplings are a known problem, good idea to change it.
2. As far as unequal temp from side to side, please provide numbers.
It is possible that some ambient (outdoor) air is being mixed in because of faulty flap doors. It is also possible that the system is slightly undercharged.
The unit of measurement you are using (kpa) is Greek to us, thought you had been posting PSI? Surely your gauge set has both?
If you can do PSI then lets have the readings lo and high at 1500 rpm, recirculate, windows down, max cabin fan, max cool setting (2 sets of number , both engine hot and engine cold) once you get the fan straightened out

We thrive on hard data!

[Autosaver]

Haha oh the scan tool gave pressure readings in kPA & not psi...

Pressure readings (Greek to English):

Initial high side pressure after car has been sitting in sun & AC first turned on 413-429 psi -> warm vent air
High side pressure after car is driven for 5 minutes 355-369 psi -> cold vent air
High side pressure when car is stopped & idling 377 psi -> cool but warmer vent air temp
High side pressure when car allowed to to free roll down hill (max air flow, low engine load) -> 311-319 psi

The scan tool is aftermarket brand so high side pressure readings might be off a little but the evidence is there, warm when air flow is poor (stationary) & cold when air flow is good (car moving).

Viscous fan is now confirmed - managed to get a look at the car this morning. Allowed engine to reach operating temp & then put a piece of cardboard in the fan blades. The fan slowed & came to a stop, finally!

As for ambient air entering AC system: removed the plenum chamber cover & found a door flap behind it. It was closed but I think it opens sometimes & also the seal maybe faulty. Most likely this is where the ambient air is entering the AC system. The motor for the door flap has been disconnected & the air entry points on the firewall have been blocked off.

Would've liked to have kept the car over the weekend so I can get some proper measurements & test drive it to see if sealing the external air door flap has done anything good.

Anyways just after sealing the door flap - temp readings were taken for drive & passenger side: 15C passenger vs. 21C driver. This 6C difference is consistent with initial readings taken this morning when AC was cold: 8C passenger vs. 14C driver. FYI the temp difference before heater hoses were pulled was 9C so a 3C improvement after heater hoses pulled. When car was driven to be dropped off to the customer the air vent temps seemed to equalize. Please don't grill me for not providing measurements/data - time constraints are a factor in a busy workshop.

I think this is going to be an ongoing job - I now realize that the AC had several faults but what made/is making it difficult is that they are not all presenting themselves at the same time & also the faults are more OR less intermittent in nature.

[swampy 6x6]

hi
Has the vehicle ever been in a crash repairer ??
use a refrigerant identifier ,also check for non condensables eg air
degas system and measure weight of refrigerant recovered

If its a PX Ranger yes they have blend door issues .
Yes the easiest way to disregard heater is to join hose feed return or just crimp supply for testing

[Autosaver]

It's an Australian import, second hand & only has 65,000km = 40300 miles !!
I don't think it has been into a crash repair shop, at least it doesn't look that way.

Flap doors/motors confirmed as there are existing error codes for 3 of the flap motors & sensors.

AC has already been recovered, vacuumed & refilled to specification.

[tbirdtbird]

Ah, nice to have psi readings back!
As you suspected clutch fan is crap, a common problem.
All your readings are too hi, and should come down with fan repair. Report back and also include ambient! Any time you give pressures we need ambient.
System will not perform well at all with readings that hi.

Have no idea about this so-called scan tool you are using.
So, you are not using a traditional Manifold Gauge Set (red, blue, and yellow hoses)?
A scan tool is gonna rely on a transducer(s) somewhere and they may have aged and reporting incorrectly. You cannot beat a direct reading bourdon tube old school gauge.

[tbirdtbird]

To be super sure, is this car R134 or R1234yf?

Easy way to tell a fan clutch is if it totally freewheels when it is cold, engine off

[Autosaver]

Car is R134a. Confirmed on Autodata service/repair system. Also I think the R1234YF service ports aren't compatible with the R134A gauges??

First 2 times car was brought in to have AC checked:

1. Viscous fan did not free wheel first thing in the morning when engine was cold & off. There was a lot of resistance when fan was rotated
2. It also passed the 'cardboard in the fan blades' test several times - fan slowed a little but did not come to a stop (engine @ operating temp)
3. Didn't bother to check for free wheeling yesterday. It was enough for me that the fan convincingly failed the 'cardboard' test (came to a stop)

@ tbirdtbird...Have you ever seen a viscous fan coupling fail @ low mileage?

I also had a look online for a TSB for the coupling. None found

We've changed the fan couplings on two other Fords with AC issues but they had done well over 150,000 km ~ 100,000 miles.