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Old 05-13-2015, 03:02 PM   #1
bpoolson
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Smile A/C always blowing hot on 2006 Lincoln LS V8

My daughter owns a 2006 Lincoln LS V8 and no matter where you set the controls on the panel it either blows wide open on "extremely" hot or nothing at all. The A/C is either not working, or something is very wrong with the controls on this vehicle. I've read older forums that all say may be the DCCV. In fact, we did the Self-Test and received a code 2798. If you can point us in the right direction, any help would be greatly appreciated. BPoolson
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Old 05-13-2015, 10:11 PM   #2
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Re: A/C always blowing hot on 2006 Lincoln LS V8

Welcome to the forum!

So her car only has one blower speed - full (and off)? That sounds like the blower motor controller. This would be independent of the issue of only having hot air from the vents though. That could the DCCV or possibly that the A/C is not working/low on R-134a. With the A/C set to be on, or the system set to Auto and a cold desired temperature set, does the A/C compressor clutch engage and stay engaged for several seconds?

With the 2798 code there's a good chance the DCCV has a fault (or the wiring to it).

-Rod
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Old 05-14-2015, 09:18 AM   #3
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Re: A/C always blowing hot on 2006 Lincoln LS V8

We have only begun to address this problem as we had to replace two ignition coils and all 8 spark plugs last night to get the car running properly again. Now on to the A/C issue. Yes, the A/C compressor clutch engages and stays engaged for several seconds. Would you suggest changing the 10amp fuse under the hood that a faulty DCCV can cause to blow as well as charging the A/C first then see what happens? Also was wondering if replacing the thermostat would help. Is there another diagnostic test that can be run to pinpoint the issue with the A/C?
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Old 05-14-2015, 01:05 PM   #4
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Re: A/C always blowing hot on 2006 Lincoln LS V8

If you have a manifold gauge set you could check the charge on the A/C system without spending money/time on an evacuate and recharge. If you tried to just add to it and overcharge the system you'll end up with an under-performing A/C system as well, so I don't recommend trying that.

You should check the fuse for the DCCV but if the fuse is good I wouldn't bother replacing it.

I suppose you could set the HVAC temperature all the way to the lowest temperature (60 or 65 degrees F if I recall correctly), then check the hoses from the DCCV to see if they get hot. If so, the DCCV is flowing coolant when it shouldn't be. Changing the thermostat won't help. The next step at that point would be to check for voltage to the DCCV. If the unit is flowing coolant but the control voltage says it should be closed, you have likely found the source of the heat -> a stuck open DCCV. I'd have to dig back in to my files to find out if 0VDC = open or closed. If 0VDC is closed, then just unplugging the DCCV and checking for heat would test if the DCCV is stuck or not.

-Rod
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Old 05-15-2015, 08:06 AM   #5
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Re: A/C always blowing hot on 2006 Lincoln LS V8

We will do the steps in your last post this weekend and get back with you on the results. One other issue has been ongoing for a couple of months now. The temperature gage jumps up to 3/4 after the car has been running for a few minutes. Hasn't actually overheated yet but afraid it may eventually. Would this have anything to do with the A/C issue?
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Old 05-15-2015, 12:31 PM   #6
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Re: A/C always blowing hot on 2006 Lincoln LS V8

I just checked my files. The DCCV closes when full battery voltage is applied, so open circuit should be full flow. You'll want to check for battery voltage to the DCCV (there's a convenient connector on the side of the radiator) with the DATC set to 60 degrees F. If you have full battery voltage there, then see if coolant is flowing through the DCCV. If so, the DCCV would appear to not be working properly (stuck open).

-Rod
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Old 05-21-2015, 04:06 PM   #7
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Re: A/C always blowing hot on 2006 Lincoln LS V8

So, took the car to a radiator shop and had them do a pressure test and they found a leak in a part directly behind the thermostat. Have any idea what part that is? It has several hoses hooked to it and is connected to the head.
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Old 05-21-2015, 11:00 PM   #8
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Re: A/C always blowing hot on 2006 Lincoln LS V8

I think you're referring to the "Coolant outlet pipe" and it's listed as part number 8A504.

-Rod
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Old 05-25-2015, 03:49 PM   #9
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Re: A/C always blowing hot on 2006 Lincoln LS V8

Where can I find detailed instructions on changing the thermostat and the attached coolant pass through hose (which doesn't look anything like a hose but rather more like the thermostat housing..but attached to the housing), which the hose to the degas bottle hooks to?
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Old 05-25-2015, 11:04 PM   #10
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Re: A/C always blowing hot on 2006 Lincoln LS V8

I'm not sure how detailed you're looking for, but I could check the factory service manual to see what it shows. If interested in that, send me a Private Message with the request and include an e-mail address that can accept PDF attachments.

-Rod
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