Gen1 LS AC Blows Hot On Passenger Side Went Through Threads

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LincolnSedan

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AC blows hot on passenger side. Have done extensive work on this. On second DCCV. First was aftermarket, second may be bosch do not know. The vendor replaced the part. Get that there are problems with some aftermarkets. The 1st one did not have any residue in chambers. This is doing the same thing it did with last DCCV. No residue in system, flushed, very clean before.

After replacing, testing with DCCV connected, one side has full 12volts of battery voltage, the other is reading about 8.95 volts (is that enough to open or close it? That is on max cool. Am wondering if I may be looking at an electronics issue like temp sensors (ie switch 2 sides)? A DATC issue with the low ground voltage on one side (one time during inline testing I had no voltage, ran diagnostics on DATC voltage came back, very weird). I did a number of wiring tests. List them below. If anyone has any ideas on what diagnostics or direction to go with this please advise? Lots of time messing with it.

I have full heat with max setting on both sides, no issues with heat. Have excellent ac on drivers side, just checked freon level, must be 38 degrees. Have never had a full heat all the time concern, always heat on pass side with ac.

Is it possible to install an inline hose pincher clamp for the passenger side temporarily until I can work on this more? Would it hurt anything as the DCCV cuts coolant off to that side anyway?

-bn/gr no voltage, reset, then 11.85 with valve connected this is battery power

-have good pin out from datc to valve for 2 grounds

-no faults on datc ever

-ran open wiring tests on DCCV wires, no opens to body

-did continuity test from DATC connector to DCCV connector, passed, read 0 on meter

-did not see any odd wiring issues when
 
It sounds like you have some blockage in the lines somewhere, ar ed you sure it's not something to do with your AC system, the Dual Climate Control valve seems to be working if you have heat on both sides so maybe you'll have to diagnose something else, I mean it is possible that you DCCV is faulty, I've ran both Motorcraft and generic brands, Motorcraft is the way to go, is your Auxiliary coolant pump original?
 
it is a 2000 with a 3.9 engine. I have max heat both sides, doubt any blockages unless it is causing the high heat? did you read my post, this is my second dccv with exactly the same syptoms. i noted the low voltage on one side of the coil, likely coming from the datc. details above. the original dccv had no residue in the valves. I have very clean motorcraft coolant in the system. I did extensive electrical testing, noted above. did you see any of that? what about interior temp sensors at the plenum or a datc? the negative voltage at one coil is about 9 volts, testing inline on battery power, is this enough to actuate the coil on the one side? could this contribute to high heat on pass side?
it is llikely the original aux cooling pump, it did not present any signs of failure. what problems can a bad one cause?
 
If the replacement DCCV is NOT Motorcraft I would suspect it was bad again. You said you don't know the brand of the DCCV. Start there.
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clubairth said:
If the replacement DCCV is NOT Motorcraft I would suspect it was bad again. You said you don't know the brand of the DCCV. Start there.
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funny everyone says it is this, after second datc, first one had condition issues, the dccv seems to be stopping coolant flow with ac on. ac is very cold, do not have to use coolant clamps. only did for diagnostics. someone said it could be a fet on the board. dont assume every time it blows hot it is a dccv. think I have a bosch aftermarket. maybe some are crap, who would know with parts suppliers what you are getting after 20 yr? where is bosch made now?
 
I'm a bit late to the party. Do you happen to have an oscilloscope to help determine if the 9V to the one DCCV valve is pulsed 12V (PWM) or actually 9V? I don't recall if the DCCV is able to get a PWM signal or not. I'm guessing not since trying to restrict water flow with a valve at a high rate is not going to be very effective usually.... Since that measurement is under load, you could also see what it reads when open circuit to determine if you might be fighting corrosion in the supply line somewhere, indicated by full battery voltage being measured under no load.

As for checking temperature sensor readings, that's going to be easiest to do using a high end scan tool that can monitor the climate control sensors in real time. Otherwise you're stuck disconnecting and measuring across the sensors and comparing the resistance against a table of expected values which should be available in the factory service manual.

-Rod
 
SHORod said:
... I don't recall if the DCCV is able to get a PWM signal or not. I'm guessing not since trying to restrict water flow with a valve at a high rate is not going to be very effective usually....
Click to expand...
The valves are actually PWM'd to control the flow. The frequency of the PWM is actually high enough that the valves don't open and close rapidly, instead, they hang partly open in proportion to the duty cycle of the PWM. It's a clever, but finicky design. I did mention to him that he needed a scope to see what was really going on, but he didn't want to go to that level.
 
Hello, hopefully ppl will not need to go that level to get ac. I get the idea. My system had a faulty datc,when replaced with a good one, the problem almost went away. I can surmise at this point the dccv is likely working properly. Initially I even changed out the dccv for a new one, got saem problem. The one I took out seemed to test normal also. Do not thing the second one was bad, may be bosch whatever.
 
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