Automotive Air Conditioning Information Forum

Hi everyone, I bought a well-maintained '05 Navigator last year, with around 110,000 miles on the odometer. Once summer came around, I noticed the A/C wasn't very cold. I put a thermometer in the dash vents and on the coldest setting, in recirculating mode, I was only getting around 49 or so degrees Fahrenheit out of the vents. This was true to both the front A/C system as well as the separate, rear A/C system. Thinking it was low on refrigerant I bought a re-charge kit. I hooked it up to the low pressure port and before piercing the can of R134A open I noticed the pressure was a little low according to the range it should have been based on the ambient temperature. The system sucked down the entire large can. I drove it for a few minutes and the A/C system didn't really improve. I bought another large can, and it sucked it right down. Drive it for a few days and the system was still putting out 49-51 degrees, and by the way, to get the temperatures down this low I had to drive it on the highway for 20+ minutes. Stop and go driving wouldn't get the temps under 55 on a hot day here in Maryland. Thinking the system must've been REALLY low on refrigerant, I added a third large can to the system. It sucked it right down, too, and the gauge never reach 40-50 PSI on the low side. Frustrated I stopped driving the car on hot days and drive my other car. A few days later, I found I had blown out the front compressor seal on the Navigator. I over-charged the system, thinking the low pressure gauge one each can I used was the ultimate deciding factor as to how much refrigerant I was needing.

At this point I did some research and learned a bit more about automotive A/C systems. I ordered a new compressor, condenser, filter/drier, expansion valves, and o-rings. I removed everything (including expansion valves), ran flush through the A/C lines on the body of the vehicle (all of the other lines under the hood were replaced), followed behind with air to blow the flush chemical out, installed everything, and used the proper amount of (dyed) PAG oil. I got a good deal on a Robin-Air Cool-Tech A/C machine, and did a standard vacuum check (15 minutes). The system passed the vacuum check...... but I noticed the needles on the high and low gauges of the A/C machine had dropped a little. I decided to run the vacuum pump for two hours to remove all moisture, and I noticed that after sitting for 40 minutes with the vacuum pump off but the system still connected, I had lost nearly all vacuum. Not sure if there was possibly a leak in the A/C machine, I used my buddy's gauges with new seals and all. We used his commercial vacuum pump in junction with his gauges, and same thing-- you could see the vacuum decrease after 10 minutes. We then pumped 150 PSI of nitrogen into the system and sprayed around several joints for leaks. Nothing. And we could watch the pressure of the nitrogen drop. I determined there was definitely a leak, but the summer was now over and I decided I'd wait till next year.

Well, here I am, 2017, it's getting warm, and I'm back to chasing down this problem. I had a buddy use his Snap-On A/C machines and do a 15 minute vacuum and recharge my system. I noticed that sitting still I was barely getting under 55 degrees out of the vents immediately after this, and on 70-degree day. I used his Snap-On refrigerant leak detector / sniffer, and check the entire engine compartment of A/C lines, under the car, the rear A/C system, etc. I was even able to pop the sniffer into the front and rear evaporator plenums. I did all of this while the engine was running and no leak was detected anywhere. I headed back down the highway to my house and after a but of driving the A/C came down to 45 degrees out of the vents. It was still only 70 degrees out, and the interior was not heat-soaked whatsoever. So it was obviously performing very poorly.

I waited till night time and took my yellow shades and my two nice UV flash lights and checked everything under the hood first. Not a single sign of a leak anywhere. Checked the condenser up and down, the filter/drier, the compressor, all of the lines, the schrader valves on the high and low pressure ports, the expansion valves.... every joint under the hood..... and nothing. I checked the lines running to the rear A/C system and they were fine. I then took my borescope and looked in the front and rear evaporator plenums-- first with normal lighting the make sure they were clean (NO debris, dirt, dust, etc on either of the evaporators, by the way), and then checked them with my UV light. No leaks there either. I've checked literally everything.

It has now been 4 weeks and I somehow seemed to be holding charge, despite not being able to hold vacuum nor nitrogen at the end of last summer, because my system continues to have somewhat cold air. On warmer days it takes a lot longer to cool down, and I always only use recirculating mode, though I've tried pulling it outside air and that didn't help of course. Today was around 77 degrees and I was able to get around 48 degrees out of the vents at best.

The buddy of mine with the Snap-On A/C machine and sniffer said it must be a bad compressor or expansion valve(s).... even though all of those are new. I'd hate to go tearing into any of those again on a whim, especially since all of the last components (the original components) gave the same problem with the system not being able to break below 45 degrees, even after hours of highway driving and the A/C on full blast (and a cool cabin temperature). It just seems like something is maxing out. The only things I haven't replaced (aside from some of the lines) is the front and rear evaporator. But again, they're not clogged with debris to minimize their efficiency, and neither of them seem to be leaking. Some might say that 48 degrees coming out of the vents is perfectly fine, but it's definitely not. The A/C seems to perform less as the ambient temperature increases, or just takes a good bit longer to cool as the ambient temperature increases, even when the cabin is relatively cool. The system should be able to get down to around 40 degrees coming out of the vents. Every Ford I've had ('92 Taurus SHO, '93 Lightning, '96 Taurus SHO, '98 Expedition, '98 Contour SVT) have all been R134A systems (what wasn't originally was converted) and all blew no warmer than 40 degrees out of the vents. And the systems didn't struggle to put out cold air when idling.

Something seems really out of whack about this system and I just can't seem to put my finger on it. I'm beginning to wonder if it's a component affiliated with the electronic climate control system (the part in the dash)... but then again, the rear A/C system is manually controlled (it uses knobs).

To further show some of the oddities, here are some pictures I took when the buddy with the Snap-On machine suggested I check my pressures with the engine running and the A/C system on. The pictures are in order, and the pressures hovered down low for a little bit, then after time started shooting up. Way up. I don't get it. The high and low pressures stay about equal, and I thought they only equalize after the system has been turned off and things settle, not while the A/C system is running??














The compressor was still cycling on and off (not short-cycling) the entire time I took all of those pictures, and prior to taking the pictures, when first connected the gauges and the pressures were on the lower side.

Sorry for the extremely long-winded post.... but I just want to make sure I explain every littler bit that I can of this entire journey I've been through to weed out any basic stuff, in hopes for suggestions of something I haven't already tried. Any solid help on this would be extremely appreciated... summer is on it's way here in Maryland and I can't go another year of 90 degree days and a really poor-performing A/C system on this truck. Thanks a bunch!!!

-Andrew

Are the dials closed on your gauges?

Thanks for the super-quick response Tim. I'll have to ask my buddy, he hooked them up while I was grabbing an extension cord for something, and I didn't check to see if they were opened or closed. My guess is open based. I'll hook the gauges back up this week, make sure they're closed, and report back. Thanks again Tim!

So I hooked the manifold back up and was sure to not open the valves on the manifold itself-- just on the high and lower pressure adapter fittings.

It was around 73 degrees ambient temperature and I was parked under a shelter, which wasn't even in direct sunlight, and I could only achieve around 50 degrees Fahrenheit out of the vents at best, and that was after starting at around 58 degrees and running full-blast for around 10 minutes. The high side pressure seems to be about where it should be, according to some R134A charts I've seen, but the low side is definitely a bit high.

I also noticed the compressor didn't seem to be cycling off. My buddy claims he heard it cut off and back on once in the 25 minutes or so that we left the system running while monitoring the gauges. The low pressure line under the hood was chilled for sure, but not cold enough to sweat (perhaps ambient temp wasn't hot/humid enough anyway?).

Here is a video of when I first started the car up and turned the A/C on, as well as a picture of the gauges, after they were connected for about 20 minutes with the engine running (roughly 10 minutes after the video ended):

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



Any ideas/suggestions??? Thanks again!!

110k miles. Probably time for a fan clutch.

I see lots of idle testing.

Do a full load test.

Doors open, Cabin fans on highest speed. Raise engine rpm above 2,000 rpm. Run the engine at that speed for at least 90 seconds, then record the pressures, the vent temp & ambient temp while the engine is still above 2,000 rpm.

Post the results.

Get thr4 pressures correct and do not forget to check the blend doors. Clamp off the heater core also.

Thanks gentlemen! I did do another test on Wednesday, but have been too busy to post the results. I went ahead and opened all 4 doors and the rear hatch, set both the front and rear A/C to the coldest setting and the fans at the highest setting, and brought the engine up to around 2,000 RPM. The A/C was set to recirculation mode.

Here is what I saw when I first brought the engine up to 2000 RPM:


And after around 1 minute and 40 seconds, here are what the gauges looked like (high side raised a little):


Ambient temperature was 84 degrees, and the car was completely in the shade. Then after 1 min 50 seconds or so, the temperature coming out of the vents was around 61.5 degrees. I kept the engine at around 2,000 RPM for approximately two more minutes and the temperature got down to around 60 degrees, but wouldn't get below that.

Today, it was dark and rainy, 63 degrees outside, and I wasn't able to get less than 50 degrees out of the vents when rolling down the highway for 5 minutes, after sitting in traffic with the A/C putting out around 55 degrees out of the vents.

I have also been noticing that when I set the front A/C to put air out the dash vents (the ones facing the passengers, not the defrost vents) and foot vents every now and then the air will stop blowing out of the dash vents for a few seconds, will continue blowing out the foot vents, and then dash vents will start blowing again. Not sure if a blend door actuator is acting up and causing that, or if that is supposed to automatically happen every so often for one reason or another.

I'm trying to make sure I understand the fan/clutch potentially being the problem. The engine coolant temperature never gets higher than half-way through the coolant temperature gauge on the dash, whether in crawling traffic or rolling down the highway. And even when rolling down the highway for 20+ minutes on a 70 degree day the A/C has not gotten below 45 degrees out of the vents since I had the system recharged recently and started monitoring the temps again. This was about the same as I was seeing last year, before even touching the A/C system.

Unfortunately I did the test before the suggestion to clamp off the heater core. Where exactly would I want to do that? I did replace the vacuum-operated heater control valve under the hood with a new Motorcraft one, thinking maybe that valve was bleeding coolant past it when it shouldn't. Seems like even the old one wasn't letting anything through... I tried blowing air through it with my mouth, with the valve shut, and no air was passing through the new nor the old one.

Thanks again everyone!

Sounds like the actuator flaps/doors need to be investigated.

Your pressures look pretty normal.

Thanks once more Cusser... that confirms my fear, mainly because I didn't want to tear the dash apart to get to the evaporator plenum. I was concerned maybe the recirc door may not be closing/sealing fully, or the blend door for mixing the heat/AC might not be sealing fully. I have no typical noises like others have experienced when an actuator goes back, but I did have the replace the an actuator for the rear last year... the one that directs the rear A/C to either come out down low or out of the roof vents was worn and allowed the door to keep opening and closing, causing a banging noise. No banging, clicking, nor anything unusual coming out the front, but whose to say something just isn't doing what it should do anymore. I guess I'll evacuate the system again and replace the blend door while I'm in there.

I did personally think that the low pressure was a bit low for 84 degrees ambient temperature. Everything I've seen says 45-55 PSI on the low side for 85 degree ambient air, and I was only seeing around 32 PSI on the low side after the nearly 2 minutes doing that last test.

The high side also seems a touch high, doesn't it? Charts say should be around 225-250 with 85 degree ambient air and I was up around 260 PSI. Am I taking the R134A ambient temperature charts too seriously? Thanks Cusser!

Your refrigerant loop is working, and moving heat.

The elevated high side is the reduced airflow over the condenser - the worn fan clutch.

Engine cooling systems have a lot of reserve. The A/C system suffers first, well before overheating the coolant.

The diverter door random operation suggests the location of the problem. If the blend door is not closing all the way, you will never get real cold.

The FSM will have the procedure for "homing" all of the door servos. I would purchase an AllData subscription for that vehicle BEFORE attempting a dash dissection. You may be able to reset things without disassembly. Even if you must get in to the dash, having the manual is a big help.