Automotive Air Conditioning Information Forum

If the evaporator lines are not cold, you have a refrigeration issue. I have run across this once before on an add on system. The drier was installed in reverse. I am not saying this is your problem but it is something to keep in mind. Without pulling up your vehicle, you may have a defective TXV Has it been changed? If so, it may be worth changing again. Did you use quality replacement compressor, drier/accumulator, and metering devices? And I do not use AC machines; I use a calibrated scale and I am careful not to let air into the system. I also do not use reman'ed compressors, only brandy new and with new control valves. I have learned my lesson with reman'ed VIR assemblies. YOU MUST HAVE cold lines entering and leaving the evaporator.

Dougflas wrote:If the evaporator lines are not cold, you have a refrigeration issue. I have run across this once before on an add on system. The drier was installed in reverse. I am not saying this is your problem but it is something to keep in mind. Without pulling up your vehicle, you may have a defective TXV Has it been changed? If so, it may be worth changing again. Did you use quality replacement compressor, drier/accumulator, and metering devices? And I do not use AC machines; I use a calibrated scale and I am careful not to let air into the system. I also do not use reman'ed compressors, only brandy new and with new control valves. I have learned my lesson with reman'ed VIR assemblies. YOU MUST HAVE cold lines entering and leaving the evaporator.

Thanks for the help Doug. Getting my fingers on the evaporator lines for the front system is pretty much impossible without tearing out the dash and cracking the plenum open, the way that the lines run from the firewall right to the plenum. I've been able to remove the evaporator temperature sensor from the plenum to be able to barely reach a finger in the plenum and touch the evaporator. I remember it being cold-ish..... but certainly not very cold. The way the lines are on my entire system, there's fortunately absolutely no way to mis-match any of the connections. You'd end up with male-to-male, or female-to-female, or different size connections that don't match up. Both TXV's were replaced with new ones. My original TXV's were super-clean and showed no sign of failure, so when I was troubleshooting these cooling performance problems one of the last things I did was re-install the original TXV on the front system, but left the new TXV in the rear system. The front and the rear system are usually within 1-2 degrees of each other on outlet temp, by the way. Last compressor was aftermarket, but current compressor I just installed is a new Motorcraft. Literally everything but the hard line sets that run to the rear evaporator, and the high and low pressure switches, have all been replaced. Condenser, compressor, drier/accumulator, muffler, expansion valves, evaporators, blend door controllers...... all of that has been replaced now. And each time I replaced the anything, I installed a new compressor, condenser, drier/accumulator, and muffler. Prior to installing the new parts, I always flushed the line sets that run to the rear evaporator, and flushed the evaporators too, except the last time when I installed brand new evaporators. TXV's have always been very clean, even when I replaced them anyway. I've always ran a vacuum for several hours using my 6.5 cfm pump that has been well-maintained, before charging the system with new refrigerant and PAG oil.

I went back to my buddy's today and after de-greasing all of my pulleys and installing a new belt yesterday, he charged the system back up with 3.6 lbs of R134a. This time the compressor operated as expected. No belt slippage, no noises, no compressor lock-up..... everything seemed fine. However, as mild as it was outside today (64 degrees at the time of the testing), in the shade, I let the car idle for 20 minutes with the front and rear A/C on the coldest setting, on recirc mode, with the blower motors on full-blast. Got a best of 56 degrees outlet temperature of around the 17 minute mark. The compressor stayed running the whole time-- it did not cycle off, while I left the car idling and watching the pressures on the A/C machine. Again, only 64 degrees outside, so the inside of the car was absolutely not hot at all. He jumped in the car after the 20 mins and held the engine at around 2,500 RPM for 4 mins or so. The outlet temp finally jumped down to around 51 degrees and settled there before he decided to let off the throttle. Here's a video of the pressures while he held the engine at around 2,500 RPM:

https://www.youtube.com/watch?v=EbWZULU0krE

We did spray some water on the condenser after this. We didn't exactly mist the water, and couldn't because his garden hose nozzle wouldn't mist, but after spraying one side of the condenser down a little the high side pressure did from drop around 175 PSI to under 150 PSI. I'm not exactly sure what that indicates, but here's a video of it. The video started literally like one second after he started spraying the condenser:

https://www.youtube.com/watch?v=jh4xv424Rpw

Outlet temp had increased while we went and got the hose out to do this, and it dropped back down to around 56 degrees after spraying the condenser.

Still under 65 degrees ambient temperature, I headed home down the highway after this. Still a comfortable temperature in the cabin (around 71-72 degrees) yet after 10 mins of driving down the highway with the A/C still on full-blast, the best I was getting was around 49 degrees outlet temperature. After having been driving down the highway 20 more minutes later, the best I ever say was 47.2 degrees. Every time I came to a stop, the temps would creep up to around 50 degrees. Honestly, if anyone tells me that's an OK temperature based on the ambient temperature and the cabin temperature..... I can't agree with that. Once it gets in the 80s and higher again, the car will be back to putting out around 62-65 degrees out of the vents while idling for a while, and MAYBE 53 degrees at best when doing normal, non-highway driving. Nothing unfortunately seems to have improved after installing this new Motorcraft compressor, aside from the clutch bearing not squeaking at times like the last one was doing after a couple of years. At a loss again with this thing.

Another buddy of mine was a technician at a Ford dealer for several years, and now has his own shop working primarily on late model Fords. He has serviced the A/C systems of several '03-'06 Expeditions and Navigators, and has been stumped by my outlet temperatures as well. He has never replaced the extent of A/C components I have replaced on any of the vehicles he has worked on, but he understands the A/C systems pretty well and has always seen sub-40-degree outlet temperatures out of them. He knows exactly what I've done each time I've replaced parts, flushed the system, did a deep vacuum, re-filled the system (he has filled it a few other times).... and concurs that everything I've done was done the best way possible. I guess one could argue using a scale instead of an A/C machine would be more accurate, but his A/C machines uses a built-in calibrated scale under the 30 lb refrigerant tank, in order to gauge how much refrigerant to add.

So once again, I'm at a total loss lol. And the problem is with the front AND rear A/C systems.... so to me, the problem must reside with a common part, such as the condenser, compressor, accumulator/drier, or muffler...... rather than expansion valves, blend door issues, evaporator issues, other plenum issues, etc.

In all of that! Do you ever list the low side pressure reading? High sider of 175 is low. Tubes on the evap mildly cool. I know you claim to have the right amount of refrigerant. Really looks like an undercharged system.

Plus not all designs work great. You can only get so much out of a system if it's working correctly.

Tim wrote:In all of that! Do you ever list the low side pressure reading? High sider of 175 is low. Tubes on the evap mildly cool. I know you claim to have the right amount of refrigerant. Really looks like an undercharged system.

Plus not all designs work great. You can only get so much out of a system if it's working correctly.

Hi Tim, thanks for the message again. You can see the high and low pressures in the two videos I posted in my previous post above:

https://www.youtube.com/watch?v=EbWZULU0krE

https://www.youtube.com/watch?v=jh4xv424Rpw

As I've mentioned before, I had a '98 Expedition with pretty much the same A/C components that produced 37 degrees out of the vents all summer long. It didn't have trouble cooling at idle, took almost no time to start producing sub-40 degree air.... it was totally opposite of this '06 Navigator with pretty much the same system. I'll check with some people on a Facebook group for Expedition and Navigator owners and see if I can get anyone with a thermometer to stick in their dash and tell me what they get, but after talking to a friend that services A/C systems on a bunch of Expeditions and Navigators over the years, he mentioned that despite everything that has been done to remedy my issue it doesn't blow nearly as cold as ones he has serviced at his shop. He has tried adding more and less refrigerant to the system to see if the temps got cooler and no dice. I'll see what evidence I can gather on other peoples' trucks of a similar year and report back

Tim wrote: High sider of 175 is low. Tubes on the evap mildly cool. I know you claim to have the right amount of refrigerant. Really looks like an undercharged system.

Something I'm trying to wrap my head around is the above statement. I know the R134a pressure charts out there are just a loose-ish guide, but I was looking at one of the pictures I took of the gauges yesterday and I had a low pressure of around 33 PSI, and high pressure of around 180 PSI. According to the charts, based on the ambient temperature at the time of doing all this yesterday (low 60's outside), I'm right about on the high end of where I need to be on my low side pressure, but I'm about 25 PSI over the range listed for what the high side pressure should have been. Where should I really expect to be at, if the charts say max of 155 PSI on the high side, when it's 65 degrees out? Thanks again!

Low 60 ambient and 47-degree vent temps. You have an issue somewhere with a low of 33psi. Not sure you're even getting a proper reading at that low of an ambient.

sounds like a air flow problem across the condenser or the condenser itself/expansion valve or even some form of contamination in the system, you should be getting your pressure readings in the open sun and at 60 degree ambient temps your pressures are too high and even set on high max output the compressor should be cycling every so often because of system ability to cool at lower ambient temperatures. contamination/moisture can come from bad pag oil, cheap refrigerant manufacturers, ac machines, improper procedures, saturated desiccant packs etc. on a cool day like that i would expect to see max 28psi on low side and max 150-155 on high, you may even be over charged. does it have a viscus fan clutch for the engine cooling fan? does it lock once engine is warmed?