Hello Everyone,
I'm hoping you may be able to provide some insight on my poor AC performance that both myself and a shop have been unable to resolve on my 2000 ford excursion 7.3L. I purchase this excursion in January of this year so I haven't been able to truly test the AC until now with these high summer temps in AZ. As soon as summer started the AC would blow cool but never cold. Vent temperatures are approximately 70 degrees out the front vents. If I turn on the rear AC system both front and rear vents then put out approximately 77 degree air when driving 45 - 50mph. The temperatures do cool down slightly (4 or 5 degrees) at higher speeds but still no where close to what it should be. I initially had replaced the orifice tube, accumulator/drier, and condenser. System was vacuumed down and re-charged but still the same issue persisted. I then went ahead and replaced all the remaining parts of the AC module since this vehicle does have 200,000 miles on it. So I replaced the compressor, front and rear evaporators, rear expansion valve, and blend door motor. Once again the system was vacuumed down and re-charged and saw no change in AC performance. High and low side pressures are correct for the given temperatures we are experiencing in AZ (both myself and the repair shop I used confirmed this). I verified the recirculation door does open/close all the way when switching between MAX A/C and normal A/C modes. At this point both myself and the repair shop are at a loss on where to go next. The low side lines do get cold enough to where they are "sweating". I'm tempted to install a variable orifice tube since I heard this at least helps the AC temps when at low speeds or idle even though I know it won't completely fix the issue. I tried checking the fan clutch by using the simple magazine/cardboard method and the cardboard isn't able to stop the fan at all so I think the fan clutch is okay.

 

Stay away from the variable orifice, check that your vacuum heater valve is closing when it's supposed to.

 

Well I verified the vacuum line going into the valve was getting vacuum. I also clamped the hose to limit the flow and didn't observe any change in vent temperatures at idle. Is it normal for the heater core under the glove box to be super hot to touch if this valve was working correctly?

 

The valve may be bad internally, they're cheap even from the dealer. Best to replace. Were all of your A/C components Ford? What are the gauges reading when connected? The T/P numbers on the gauge will ell you what temp the coil is based on the pressure, at which point you can verify by feel, or a clamp on line temp sensor at the evap coil.

 

Make sure you're testing in the MAX A/C position. That's the only one that should supply vacuum to the valve and cut off coolant flow to the core.

With the valve closed or with a heater hose pinched off, the heater core should not be HOT.

 

Outside of the valve, maybe check your condenser to see if it's clean/clear of debris and that the gap is set properly on the compressor.

 

Broken recirc door? Pull the blower motor and check it out. Mine wwas messed up and just taped it shut. Wasn't pulling the dash apart to fix in 100 heat. Thats a winter project.

 

Heater core shouldn't be hot, but did you change the thermostat also? They do fail and it determines when the compressor cuts out due to the temperature of the evaporator. Thermostat could be out of range and cycling the compressor too soon or not running the compressor long enough.

 

The 2000, and 2001 cycle the compressor on the suction line pressure switch.

 

Maybe you need more cooling air going through the condensor...does it gets super hot? I am experiencing the same and installed a pusher fan in front of the condensor and is there a fan shroud?

 

I know the compressor is new. But have you verified the air gap on the clutch with a feeler guage?

 

A mobile mechanic told me last week, that if you use aftermarket parts, their capacities may be greater than stock. Therefore, they tend to require a slightly higher charge to get correct performance.

I’m going to bump my system up a little at a time and see if this is a factor on my, similar, poor performance.