How to: Evaporator core replacement. | Ford Explorer Forums - Serious Explorations

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How to: Evaporator core replacement.

OneofMany

Well-Known Member
Joined
December 21, 2012
Messages
225
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City, State
Georgia Mountains- Talullah Falls
Year, Model & Trim Level
94 expl 4x4
It seems to be a common failure from what I have read that the top pipe into the evap core breaks off inside the air box. Here is what I did to replace it (not necessarily in perfect order):
Disconnect battery (-), Remove Air filter housing top, bottom and intake duct to throttle body. Unbolt coil pack and move away from the air box. Disconnect vacuum lines to vacuum reservoir and move aside. Disconnect electrical connectors to the low pressure switch of the a/c accumulator and the blower motor and blower resistor pack. Disconnect heater hoses behind the heater control valve leaving the short hoses to the firewall in place- they are harder to undo and easier to mess up. Not much coolant will leak out. Using a 10mm deep well undo 4 nuts holding the air box to the firewall. 2 on top and 2 below. Raise passenger side front of the car and remove the inner fender to access the 2 nuts on the bottom of the air box. Lower car and remove valve core from tire to give you better reach into the engine compartment if needed. Disconnect a/c lines to accumulator whenever convenient in this process and remove it. I assume the system is already evacuated/empty, disconnect lower pipe into evaporator core. Tape up remaining open a/c lines to prevent contamination. Remove Air box. Open up the 2 halves and clean the inside and swap out the evaporator and install new orifice tube. seal air box with silicone and fix damaged insulation to the exterior of the box. Do not leave A/c lines open any longer than needed.
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Reinstall Air box. reconnect lower evap a/c line, install the accumulator remembering to swap the low pressure switch off the old accumulator to the new one. Reinstall everything else. Remember to lube all O rings with Pag oil. Since we did not remove the compressor we probably did not loose much Pag Oil out of the system, so adding 2 oz should more than do. Draw vacuum on the a/c system for 1 hour, then let sit 1 hour to see if the internal pressure raises. You want to be able to draw at least 29 in HG of vacuum. If no leak is apparent, continue to draw a vacuum for several hours. patience is a virtue. Recharge system and check for leaks with a spray bottle of soap water. I do not go into full detail on recharging and testing as I assume some level of A/C service knowledge and info is widely available. I will gladly advise though. Note that refrigerant and capacity is not universal over gen1 explorers. Look it up.
Tools in case you are not super equipped:
3/8 ratchet, swivel, long and short extensions, 10mm deep, 13, 17.
A/c line disconnect tool
1/4 ratchet, extension, 8mm and 10mm.
needle nose pliers
pag oil (for r134a systems)
crescent wrenches to undo the a/c lines
a/c O-ring assortment as not all O-rings will be supplied with the evaporator and condenser.
Vacuum pump, gauges, refrigerant r134a ('94 and up) and adapter to connect refrigerant cans to the gauges.
 



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I got all of that except for removing the air valve from the tire (?). Perhaps my '94 Limited is a bit different than others, but I did everything from either the engine compartment or the passenger side inside (R & R the evaporator unit), didn't need to remove the fender liner to reach the two bottom fasteners. Since the unit was N/F when I bought it and I didn't get to rebuilding the A/C for a couple of years, I flushed the system after replacing the evaporator.
Be sure to test the blower on all speeds when you're finished. I had to clean the resistor connector on the side of the case to get it working properly - just had maximum blower speed (and off, of course) until I did.
Pictures do help! Thanks for taking the time.
 






I kept finding myself on my toes trying to reach into the engine compartment, so I got tired of that and pulled the schrader valve out of the tire making it much more comfortable. Not really needed but if one has a compressor.....
As to the inner fender I think it helped make it easier.
 






That makes good sense. I have a 2-step stool that gets me high enough. I need it for my '86 F-150 - and washing the roof.
 






Thsi is great, thank you! I need to replace (and clean out the airbox) of my leaking evaporator core. Also, once putting back together, does anyone know what the foiled insulating wrap/shield is called and how can I find some to replace the disintegrated wrap in my '94 XLT (with factory A/C)? No luck yet finding any part number or mention of it online.
 












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