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Hello all,my 99 7.3 seemed to have low fan airflow and cool (not cold)ac,so I looked to see if evaporator dirty,it was REAL bad,almost 90% plugged,from PO,I then had the fun job of pulling fan and making a copper tube attached to garden hose to blow it out,took an hour but my vents blew much better,then on to warmish ac,I went to napa and got a heater hose shut off valve for 15$ and that alone dropped my vents 10 degrees so making progress,then I cleaned condenser out real well,another 2 deg maybe there,then put gauges on ac and sure enough low pressure,after a few cans of good ol 134a we are off to the races with max ac at 93* outside ambient and vents putting out 48* BRRRR.The best thing is in vent position it was adding heat from htr core at coldest position,with heat valved off now I can be in vent alot more on cooler day,yippee.
Awesome ! I too suffered from my air flow not being strong. I had replaced my fan motor years back and thought the new fan was just not up to snuff with the oem one since i got a off brand fan.
So last weekend i pulled the fan to check the evaporator. Yep stuffed full of crap. So i shop vaced out what i could using some homemade attachments. Then on to the simple green mixed with a little aluminum brightener bath via a pump up sprayer and a good high power rinse. Then a nice shot of 140psi air to get the thing dried out.
Ensuring Air can Flow across Condenser/Evaporator is ESSENTIAL to good cooling. All my vehicles get cleaned annually!
"Most" A/C issues with these systems can be attributed to the following order:
Air Gap / Clutch
High/Low Pressure Switch (These are notorious for one next to the Oil Dip-Stick Connection)
Proper Amount of Freon and PAG Oil (too much, or too little, something will fail in time). "Most times, if your compressor is on/off quickly, repeatedly, this is where to look first with Gauges and a Temperature/Pressure Chart
Condenser Blockage Internal/External
Evaporator Blockage Internal/External
Orifice Tube Blockage - Internal
*Internal is almost always an indication of Compressor Failure / Replace Compressor, Flush Lines, Replace Dryer, Condenser, at a minimum*
Receiver Dryer Full
As for the older units, there is no isolation valve for the Heater Core. They depend on a "Good Operating Blend Door". At this age, they all suck by now. Adding a valve is definitely a consideration.
I replaced my compressor, accumuator and orifice a year and a half ago, flushed everything else, and it was good for awhile. Then it had a hard time keeping up on 100 degree days, so I threw the gauges on it and found the high side was too high. The orifice was plugged from deteriorating 17 year old hoses. Now everything but the evaporator is new and I'm getting 48 degrees around town and 40 on the highway in 115 degree AZ weather.
Hello all,my 99 7.3 seemed to have low fan airflow and cool (not cold)ac,so I looked to see if evaporator dirty,it was REAL bad,almost 90% plugged,from PO,I then had the fun job of pulling fan and making a copper tube attached to garden hose to blow it out,took an hour but my vents blew much better,then on to warmish ac,I went to napa and got a heater hose shut off valve for 15$ and that alone dropped my vents 10 degrees so making progress,then I cleaned condenser out real well,another 2 deg maybe there,then put gauges on ac and sure enough low pressure,after a few cans of good ol 134a we are off to the races with max ac at 93* outside ambient and vents putting out 48* BRRRR.The best thing is in vent position it was adding heat from htr core at coldest position,with heat valved off now I can be in vent alot more on cooler day,yippee.
Are you cleaning just the side you can get to by taking out the fan? Were you able to clear the other side too?
Yes by pulling blower under hood(vacuum pump is a little in the way,I pulled mine out to get fan out of housing)i used a mirror on a pivot to see whole evap as i cleaned with water,if you go in short bursts the evap drain takes it away to ground,I did stuff a few rags in area that goes in cab but no water made it in there,it smells better too.I had my boy run all blower speeds while running it in my hand and it hauled *** so I new motor was good just bad flow.
06-17-2017, 09:55 PM
