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Chris (aka- Moose)
Chris (aka- Moose), Technician
Category: Lincoln
Satisfied Customers: 47945
Experience:  16 years experience with Lincoln
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Lincoln LS: 2000 Lincoln LS 3.9LI have a problem with the

Customer Question

2000 Lincoln LS 3.9L
I have a problem with the ac on this car. I know that the DCCV is not working correctly so I can clamp off the hoses to ensure that there is not hot coolant in the heater core. The car had 70lbs suction pressure and 150lbs head pressure and was not cooling at all. I could get a small amount of cool air out of the vents if I ran the engine rpm to around 3000. When I shut it off the pressure would equalize over a few minute period. I assume that to be an expansion valve problem. I went ahead and replaced the expansion valve, compressor and receiver dryer. I can only get the car to take about a can and a half of 134 and have the exact same symptoms as before pressures and all. The car should take about two and a half cans. That makes no sense to me whatsoever!
Submitted: 2 years ago.
Category: Lincoln
Expert:  Chris (aka- Moose) replied 2 years ago.
I will need to know the ambient air temp and humidity level. I am going to look over the chart which i have included in a file below based on the temp being 80 degrees. So that would mean the high pressure is fine and the low pressure is to high. A low side restriction is the most likely culprit, restrictions come from things coming apart like the compressor or drier. Since you have replaced the expansion valve that leaves the evaporator. Did you pull a 30 minute vacuum after replacing the valve? You want a excellent 5 star answer & I would like to be rated the same for providing it. Consider I don't know your skill level & I can't see, smell, hear, or touch the vehicle. It may take a few back and forth replies. Try your best to respond with good detail so I can do the same. I normally log in at 3pm and work late. A rating is required. Your rating me, what I type. I am not an employee of this website, nor have control over the fees or the time it took to get a response. If you rate negative or not at all you still paid, but I get nothing. I want you pleased with me and my efforts, so let me know if your experience here has come up short.Thanks Chris
Customer: replied 2 years ago.
I pulled a 2 hour vacuum. The temp outside was 90. I did flush the evaporator when we had it out.
Customer: replied 2 years ago.
I don't mean to tell you your business but I believe a restricted suction line would cause high side pressure to be high and low side to be below normal.
Customer: replied 2 years ago.
High suction pressure is, in my experience either an open expansion valve or a leaking suction valve on the compressor. Because it takes a couple of minutes to equalize this points to expansion valve. I am at a loss because I just changed it and have the exact same problem. This makes no sense to me. I have been a mechanic for over 20 years and have never seen this. I just didn't know if there was something in the Lincoln system that I didn't know about that could cause this.
Expert:  Chris (aka- Moose) replied 2 years ago.
You can compare my response to the chart I sent from Ford.At 90 degrees under 60% humidity. The high should be 150-190 and the low side 38-66 your at 150 and 70. So your high side is normal to low and the low side is high. According to the chart that leaves the expansion and low side restriction. now that I know the temperature it was tested at, the compressor can also be to blame for low performance within.