92 XLT 4WD - A/C Mystery

[cdarmy]

Ok, let me just get to it:

Compressor - replaced less than year ago
Condensor - replaced less than year ago
Accumulator - replaced less than year and 1 month ago
Low/High Gas Line w/Muffler replaced a month ago
Evaporator - replaced yesterday
Orifice Tube - replaced 2 times less than a year ago and yesterday

Heating side:

Water Pump - Replaced 2 months ago
Thermostat - Replaced 2 months ago
Radiator - Replaced 2 weeks ago
Heater Core - Replaced 2 months ago
Clutch Fan - Replaced less than a year ago
Fan - Replaced 2 months ago
Prestone reverse flush kit

Have Manifold gauge set / Harbor Freight R-134 Vacuum Pump / Plenty of R-134 already gone.

Last year when I got the vehicle I replaced the Compressor/Accumulator/Orifice tube and noticed the orifice tube experienced black death. Ended up replacing the tube again and exchanged the compressor and changed the condensor out as well. Was working almost ok after vacuuming the system with pump and filling with just over 2 12oz cans but a check at a friends A/C shop showed that the High Side seemed a little too high. Ended up driving up to live in CT and noticed the system was getting warmer. When I ended up in CT the high pressure line had a leak in it and all the r-134 escaped and the line needed to be replaced. I replaced that last month along with new accumulator. After vacuuming and refilling the air just never got "cold". A week ago the high pressure released and spewed out 134 under the hood. So needless to say the pressure was just too much. I went out and got a new Evaporator/Orifice Tube since it has 195,000 miles and the only thing I hadn't changed was that. Well after new orifice tube/evaporator new r-134 and vacuuming the system, it still never got "cold". I didn't see the High High pressure I had less than a year ago and the top evaporator line was sweating nicely as well as the top of the accumulator except for the "cold" vent factor. I went and vacuumed out the whole system again got a scale and put in 2 12 oz. cans and a couple more ozs. of another all the time with the gauges attached from vacuuming to filling. Noticed that it was sweating when I had about 1 1/2 cans in (12 oz. sizes). Regardless it took it in slowly and since the manifold gauge hoses can hold up to 4 oz. I probably got just about 24 ounces in the system. However it is just not COLD! So tonight I hooked up the gauges and put a thermometer in the vents and I came up with the following:

Ambient Temp: 75
Max A/C switch setting

Fan setting low:
Low Side Temp: 38 High Side Temp: 147 Vent Temp: 50

Fan setting 2:
Low Side Temp: 44 High Side Temp: 153 Vent Temp: 55.5 trending up

Fan setting 3:
Low Side Temp: 46 High Side Temp: 154 Vent Temp: 58.1 trending up

Fan setting MAX:
Low Side Temp: 50 High Side Temp: 159 Vent Temp: 62 trending up


The accumulator/top of dryer have tons of sweat on them. I am completely stumped at this point as to why I can't get "cold" air. The only thing I can think of is that the compressor just can't get the variation in pressures. I don't have a blend door so it can't be that issue.

I am ALL EARS and am looking forward to what you other experts could add to help me get away from this obsession by solving it and move onto other things I have to get done. Thanks ahead of time!!

Carmine

 

[ma96782]

Ambient Temp: 75
Max A/C switch setting

Fan setting low:
Low Side Temp: 38 High Side Temp: 147 Vent Temp: 50

Fan setting 2:
Low Side Temp: 44 High Side Temp: 153 Vent Temp: 55.5 trending up

Fan setting 3:
Low Side Temp: 46 High Side Temp: 154 Vent Temp: 58.1 trending up

Fan setting MAX:
Low Side Temp: 50 High Side Temp: 159 Vent Temp: 62 trending up

Temps or Pressure???

http://www.ackits.com/aacf/ptchart.cfm

Aloha, Mark

 

[ma96782]

Regardless it took it in slowly and since the manifold gauge hoses can hold up to 4 oz. I probably got just about 24 ounces in the system. However it is just not COLD!

I assume that you've checked for leaks?

Because, it's a conversion...........remember the R-134a (stock system in a '94 Explorer) has: a bigger condenser (I've heard), an additional heater manifold cutout system and uses a blue orifice tube. Not to mention that it uses 36 oz. of R134a.

So your 24 oz. may not be enough. Check.......(use it as a guide)

http://www.napabeltshose.com/news/in...&show=newsitem

Anyway.......since it's a conversion........you might want to keep adding R-134a and monitor the temps. Stop, when the temps drop to it's lowest level and just begins to climb back up.
________________________________________

I wrote these a while back............

R-134a Ford - Conversion Notes:


IMHO......IF the system is still under R-12 pressure (and/or was not functioning)….you’ll be ahead of the game.…if you take it to a pro. Find out, if it only needs to be topped off or, if there is a leak or, if the compressor is up to the job. A pro, can test the compressor and usually has the tools to test for leaks, using a dye or with an elec. sniffer. IF you decide to proceed w/ a DIY CONVERSION job, you’ll now KNOW what part(s) will be needed and the system will still need to be evacuated anyway. The machine to recover R-12 is expensive and it is against the law to vent R-12 into the atmosphere. So, let the pro do that part.

Once void of refrigerant......you could DIY the parts replacement part.

IF you know that a part is bad……now (during the conversion), will be the time to replace it. IF the compressor has failed, you‘ll need a new one and YOU’LL NEED TO FLUSH.*

The usual conversion, will require the removal of the accumulator, orifice tube, and old compressor (w/clutch). Drain the oil from the old compressor and note the amount. Drain the oil from the old accumulator and note the amount. Dump the old accumulator and orifice tube, buy new ones.

Talk to the parts counter guy about your conversion......make sure that the desiccant in the accumulator is for R-134a. And, ask IF you'll need to replace the low pressure switch and/or change colors on your new orifice tube (to be compatible with the switch to R-134a). They may have it listed.

DO NOT expose the new accumulator to air.........keep the shipping caps on. Even when it's installed and hooked up to the lines.......the accumulator will draw moisture out of what little air is in the lines. For that reason, once it’s hooked up, do the re-charge immediately........or at least that day.

The old compressor can be re-used if serviceable. Do not flush a compressor.
_________________________________

Hummm……To FLUSH or NOT, you decide.

One of the reasons for a flush of the remaining components.....is that, as much as possible, you want to clear the “crud” and old oil out of the system. I wouldn't want to mix mineral oil used in an R-12 system with the oil needed for an R-134a system. But, that's just me.

So…..the evaporator and condenser can be flushed in place (or removed and flushed)......be careful. You could also flush the lines.......but, flushing a line w/a muffler is not recommended. So, you could buy a replacement hose w/ a new muffler or skip that line/part.
_________________________________

As long as MOST (say more than half) of the old mineral oil is removed and IF there was NO compressor failure…..according to the Haynes book: "Unless the vehicle manufacturer - or the aftermarket kit instruction sheet specifically recommends flushing the system during the retrofit procedure, you can assume that flushing is not necessary (Readers who obtain the SAE's J1661 document will note that it recommends flushing before retrofit. However, you can disregard this information because the SAE no longer believes that flushing is critical to a successful retrofit.)"
__________________________________

Anyway.....replace all the old "O" rings with new green "O" rings. Use Blue Nylog as a lube for the “O“ rings, in a R-134a system.

As for AC oil….use the correct compatible type and weight, keeping in mind the particular manufacturer of the AC system and refrigerant type. Oil is added into the individual parts as they are installed. How much oil? The answer varies. A good book on the subject will help.

Install all of the parts and connect up all of the lines and hoses. Once everything is back into its place..........you'll need to add on the new R-134a adaptors and label the system w/ a R-134a conversion sticker (so, the next guy will know).

Vacuum test for leaks then proceed with your re-charge procedure.

Full Re-charge:

http://www.explorerforum.com/forums/showthread.php?t=158183

Note: System pressures and capacities will vary between mfns and applications (again, a good book will help).

Ford Conversion Notes:

My '94 Explorer (w/ factory R-134a) used a blue orifice tube. I’ve heard that previous years (R-12 systems), used a red orifice tube. Normally......I figure, IF the factory system worked well w/ whatever colored tube......then, I should replace the tube w/ a like colored tube. Thinking - that the orifice color, indicates a certain sized hole. But, in this case (R-12 to R-134a conversion) a switch from red to blue orifice tube might be the correct choice.

Also, check that the low pressure switch is the correct one for your application. NAPA lists different part numbers for an R-12 vs. R-134a system (remember to also check the elec. connectors).

Shamaal said:

The switch on the accumulator controls the clutch on the compressor. When the system pressure is less than 24.5 psi the clutch is disengaged. When the pressure is greater than 43.5 psi the compressor clutch engages.

And, as a COMPARISON ONLY.......the Haynes book says ('94 Ford Explorer w/factory R-134a system)........at ambient air temp of 80 degrees F, hi velocity shop fan in front of the condenser at it‘s highest speed, engine on at 1500 RPM, windows up, doors closed, AC set at Max, fan speed at it‘s highest (I‘ve found a lower speed will give a colder reading), thermometer in center vent.........you’re looking for ………22-50 low side and 160-250 high side pressure. Capacities: oil 7 oz and R-134a 2.25 lbs (36 oz).**Conversion capacities will differ, for a R-134a conversion, I've heard figures anywhere from 60-90% of the R-12 charge was good. ** Check your temps against this chart…..

http://www.ackits.com/aacf/ptchart.cfm

AND, there was another time when I wrote..............

Remember I'm NOT a pro.......so, assume: There are NO LEAKS, the AC compressor & clutch, radiator fan & clutch, are up to the job and the system has been evacuated........

When you're re-charging the system......to start, charge it (into the vacuum) with whatever it'll take w/ engine “off.”

Then, set up a high velocity shop fan in front of the condenser and let her rip (highest speed). Turn on the engine, running at 1500 RPM, set the AC (max), *blower fan speed set at highest speed, doors closed and windows up, 10 mins. running to stabilize the system. *I have noticed that a lower blower fan speed, will get you lower temps. And, the HAYNES book says, blower fan speed at lowest speed, for the "Final Performance Test."

Continue to fill the system (w/ R-134a) to 60% of the R-12 charge. Sometimes, to help get the 60% in there, you might need to use a jumper at the low pressure switch connector, to get the compressor working. Once you get the 60% in the system, remove the jumper, reconnect the low pressure switch and observe that the clutch is working. IF the clutch doesn't energize, you may need to add a little more refrigerant (or the low pressure switch may be broken). IF you see that the compressor clutch is working. Check the ambient air temp and compare it w/ the vent temp. At an ambient air temp of 75-80 degrees F, you're looking for a 35-45 degrees F at the vent (about a 40 degree F difference, though close enough is good to). If you don't get the temps you want.....continue to add refrigerant (in the past, anywhere from 60-90% of the R-12 charge was reported to be good).......mindful that too much is no good and too little is no good......so, watch the pressure and temp readings.

Ambient air temps are taken 2” in front of the condenser. Vent temp is taken at the dash vent closest to the evaporator (usually one of the center vents).

Note the total charge and pressure readings, for future reference.

Aloha, Mark

 

[manaen]

You did add oil right? because you only mention adding the r134a but the system needs to have a specific amount of oil as well. (should be on the hood sticker) unless your using the premixed r134a

Your high side seems a little low and for the ambient temp your low side seems a bit high. So if I had to guess I would say that there is either a pump problem, or an orifice problem(too much flow), but without further testing it's hard. Did you flush everything really well when the system blew a line? it's doesn't take long for moisture to get in there, I would even go as far as using a little 134a to flush the lines while the vacuum is hooked up.