Hi All and thanks for all the great work you guys do for us here...
I posted about this last year and then the weather got cooler so I am back at it again ...

Last summer I replaced the entire AC system on my 1988 E150 conversion van with a front AC unit only.. I went back with R12 as that is what all the parts were originally designed for. I also used 10 ounces of Motorcraft YN-9 mineral oil as the book called for. The book said it would take 56 ounces of R12 + .25-0... I used 4, 14 ounce cans so that should have been 56 ounces..

The AC never cooled like it should... I took the van to a shop and they checked for leaks. That guy said it needed some more freon so he added another 14 ounce can...... I don’t think it needed it.. That made no difference in how the AC cooled...

I have noticed dirt/dust collecting around the front of the compressor so I am guessing it could have a small leak around the shaft seal on the E6DH or FS6 type compressor...

SO back to this summer. It is cooling about the same as it was last year.. The van gets quite hot inside in the middle of the day when parked. The temp inside will go over 110F that includes cloth seats, walls, and carpet so I know there is allot to cool. During the middle of a hot sunny day the van will not even began to cool down in the rear 100f after driving for an hour. middle seating area will be around 85 and the front area temp will cool down to around 75.

Last week I drove abut 3 hours of the evening on a cloudy day with the outside temprature around 90f and the whole van got quite cool to where I had to turn the fan down. When I opened the rear doors you could feel the cold are falling out..

So today I hooked up the gauges and took dome readings. I have some pics and videos along with the vent temps. I do not have anything right now to use to check the line tempatures but can buy a laser thermometer if I need to.

One thing I noticed is that the from the time the pressure switch opened it was about 7 seconds before it would close again no matter what the rpms of the engine.
SO here is what I recorded..

It was 88f outside
inside temp was 96f
humidity 56%
This pic is right after hooking up the gauges without the engine running.
Sorry the pics are upside down..



This video is probably 30 seconds or so after starting the van. The time it took to get back around to the front. It is with the engine cold and at normal start up idle set by the PCM maybe 1000 rpm's. I don't have a tach so I am not sure.
https://www.youtube.com/watch?v=6qT4...ature=youtu.be



This pic is what it settled down to after the engine was up to temp. The center vent temp was 54F





This next video was after the engine was up to temp and I am guessing around or over 2000 RPM's. The vent temp was bouncing from 54f to 56f
7 seconds cut out and 11 seconds running
https://www.youtube.com/watch?v=2X9p...ature=youtu.be



This video was after after it had cooled down to 78f in the middle of the van and I had lowered the RPM's just a little,, maybe 1700 or 1800. Center vent temps still 54 to 56f.
7 seconds cut out and 21 seconds running
https://www.youtube.com/watch?v=gLMM...ature=youtu.be



And this last video was after lowering the rpms just a bit more, maybe closer to 1500. inside temp down to around 76 in the middle of the van. vent temps 52 to 55..
7 seconds cut out and 39 seconds running
https://www.youtube.com/watch?v=RhD-...ature=youtu.be


Well what else do I need to check?

When I installed the new condenser and evaporator I did not flush them out....

Thanks
Anna

 

If I am reading this chart correctly (off google search) ,,, R12,,, with the humidity at 56% and the outside air around the van between 85 and 90f,,, This chart says the pressures are within range as well as the vent temps..

My manual has some charts and from what I figure if I am using the charts correctly,, I have a problem ...
I will post the charts from my manual in a bit...

 

Ok here is the worksheet and charts. I am not sure if I did this right or not... But the red dots represent the figures I come up with (from my understanding of how it works) I used the figures from the last video where the engine was around 1500 rpm's which gave me a 7 second off time and a 38 second on time

 

I see three data plotting errors:

1) On the upper left graph, Cycle rate per minute, should be 38+7=45 seconds, then because it is per MINUTE, need to divide 60 seconds by 45 seconds = 1.33 for the Cycle Rate per MINUTE. So that moves your red dot just above the band.

2) High side pressure, you have it about 270 PSI, I only saw 235 PSI on the 1500 RPM last one video. That puts the red dot in the range.

3) Lower right graph, Clutch ON time, move dot up about 10 seconds worth, still below the band.

My overall observation: Look at the R-12 Temperature scale on the low-side gauge just before the clutch drops out... it's down to 25 degrees or so. So it appears the evap is getting nice and cold. Overall action of high and low sides when running and cycling look good. Only real deduction from the charts is that it is cycling too fast - needs to be staying ON longer. BUT if it stayed ON longer in the conditions monitored, the evap would start to freeze. But yet the outlet air temp is too warm.

So... Is there a problem outside of the refrigeration cycle? Like poor airflow through the evaporator? Or picking up underhood air via a leak? Blend door problem mixing in heated air, wouldn't take much hot air to raise it? Is the recirculation/fresh air door sealing tightly to recirc?

My observations on A/C performance testing vehicles: It is very easy to pick up very hot underhood air blown from the engine fan, as the hood is open to use manifold gauges. Using a non-recirculate inlet air position will take in very hot air through the cowl vent, throwing off the test. Which is why they specify Recirculate (Max cool).

Just my thoughts, I'd be looking for those other issues rather than the A/C itself.

 

Pinch off the engine coolant flow to the heater core and then make sure the vents are set for recirculate.

 

Thanks for the education and advice on what might be going on Torky2. Geez and the simple addition equation...... believe it or not I even know my times tables!
I think I corrected the data plotting (In green).
I have not had time to check the pressures and vent temps when the temperature is below 80 and the van is not already 100 inside to start with... I don't know if that would tell us anything useful either that we don't already know...

In this next video the conditions for doing the data plotting were not even close so the chart cannot be used... It was around 9am, sunny, the outside temp was already 87f, and the van was over 100f inside. I had just started the van and not sure if the engine was up to temp.. The engine was running on its own start up high idle so I am not sure what the rpm's are..

Here you see the high side is around 190 to start with and within 56 seconds drops to 175 while the low starts at 28 and drops to 27..
I would think that is probably normal given the conditions..
https://www.youtube.com/watch?v=8-W9...ature=youtu.be

Yes it was on recirculate and the fresh air vent does move back and forth and appears to close all the way.
The radiator was cleaned and rodded out by a shop last spring and the condenser is new. The fan shroud is on and it has a new heavy duty NAPA fan clutch which seems to stay engaged till I reach a little over 45mph. Now there is a fairly large trans cooler on the upper right side of the condenser and I have never cleaned it though it visually appears to be clean.
And YES the air around the engine compartment gets very hot.. I had open toed sandals on when checking the pressures and my feet got hot enough to where I had to move them out from under the radiator area.
If I remember correctly my moms 78 E100 has insulation on the outside of the heater case. I wonder if it might do some good to insulate mine and perhaps parts of the suction lines that are exposed and maybe the accumulator?
So I remember after putting the evap case back on and installing the accumulator, that I noticed the gasket between the evap case and firewall was slightly off in one small area but was still under the case. Of course it had to be behind the accumulator on the side you have to remove the accumulator to access. I will use a mirror an try to recheck that.

I have a new Motorcraft heater core I bought last winter just because it was dirt cheap and mine may be original.. So I am thinking it is not that bad to remove the inside heater core/condenser case/cover to inspect the gaskets and doors. That would be a good time to replace the heater core.. Not that it needs the new heater core but if it is original, I am sure it will spring a leak at a very inconvenient time.
When I was younger I used to procrastinate wold find myself adding antifreeze the day the weatherman said we were going to have a hard freeze. It would normally be night time and already 32f... As i have gotten older I seem to have gotten over that somewhat...


Yes ProhectSHO89,, I will try that. The parts store says there is a heater control valve for my van but my manual does not show one, the van does not have one on it, the hoses look original stamped Motorcraft, and there is no vacuum line laying around to go to it.
Last fall I did disconnect the compressor clutch and ran the system on MAX AC recirculate with the temperature control on cool and there was not heat cumming out the vents, but that may not do the same thing.. I had a valve cover leaking and that was the only way to stop the smell from coming inside till i fixed it.. But i will check that out too.

OH as to RPM's again I was not sure. I have a old Dwell, tach, volt meter I am going to try to hook up and see if I can use it to read the RPM's. I am thinking that if the rpm's were above 1500, that might be what is causing the short cycle time.
Thanks
Anna

 

Ok an update. but didn't have gauges hooked up..
3am
Idling in drivway
outside temp 75f
humidity 87%
inside van middle seat temperature 65f
center vent temp 54f
Suction line feels very cold at evaporator and sweating but not icing up.
From the accumulator the suction line runs across the firewall to the left side of the engine. A second line connects to that line and on to the compressor. That connection is sweating and pretty cold but not as cold as at the evaporator.
The liquid line leaving the condenser is lukewarm. At the evaporator it is still warm but feels a little cooler then at he condenser.
Clutch not cycling at idle (staying engaged).

Drove down the road a couple of miles and vent temp stayed around 52 to 56.
Clutch cycles while driving.
Once back home and parked with engine idling, after 5 to 10 minutes no cycling (staying engaged).
Windows fogged up.

I guess I should hook the gauges back up the next time I get a chance to work on the van under similar conditions?

Remember I said that shortly after I originally charged the system I went to a shop to have them check for leaks and they added a 14 ounce can.. Any chance it could be a little overcharged?

 

your pressures look good for the outside temps.
i think the biggest problem you have is this is an older system that just is not efficient enough for the size of big sweat box it is trying to cool.
if you had the dual zone AC in the van it would do much better.
i had a 75 suburban with the dual zone AC and it would only get cold inside after hours of driving in the summer.