DCCV Fuse. Check it!

Jim Henderson

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We all have had or will have a failed DCCV Dual Climate Control Valve fail on us. Common symptoms are hot air from one or both sides of the cabin vents regardless of what the control is set to.

Replacing the DCCV is not hard. But I don't recall seeing that we should also check the fuse that is often blown when the DCCV fails.

The fuse in qustions is one of those Micro fuses, tiny square ones with probgs. 10A I believe. It is fuse #1 in the underhood fuse box. On my 2004 LSV8, this box is on the front of the passenger side fender.

I have even had this fuse blow once or twice when the temperature control system seems to be working properly. Probably just a system glitch. If the fuse is blown you will have all the symptoms of a bad DCCV even if like on mine, the DCCV is new.

Just replace the fuse, maybe a 3 minute job and something like $1 for the part unless you buy a pack full.

Good Luck,

Jim Henderson
 
I have even had this fuse blow once or twice when the temperature control system seems to be working properly. Probably just a system glitch.

It's not just a glitch. It's because one or both of your DCCV solenoids coils are starting to short to the metal frame, very near the positive side of the coil. (Alternately, it could be the compressor clutch coil, but that is rare. DCCV shorts are not rare.)
 
I have even had this fuse blow once or twice when the temperature control system seems to be working properly. Probably just a system glitch.

It's not just a glitch. It's because one or both of your DCCV solenoids coils are starting to short to the metal frame, very near the positive side of the coil. (Alternately, it could be the compressor clutch coil, but that is rare. DCCV shorts are not rare.)

I am glad you chimed in with the "why", as my response would be along the same lines: fuses do not blow unless there is some contributing factor.
 
I am glad you chimed in with the "why", as my response would be along the same lines: fuses do not blow unless there is some contributing factor.

I have no idea what my problem was but I recharged the system and the fuse doesn't blow any more. My fuse started blowing last fall, thought it was the DCCV, changed that in the winter and everything ran fine until spring when it blew again. Charged up the ac system and it has not blown.
 
Might be time to check the coolant level in the AC. But glitches include intermittant shorts in my mind. The problem is finding intermittants, a pita. The DCCV in my car is maybe 2-3 months old, but there is always infant mortality. I prefer and hope it is a glitch.

Either way, if you replaced the DCCV, you need to check the fuse, it is probably gone too. I don't see that mentioned much, if ever. I think I saw it on a Jag site instead.

Jim Henderson
 
I shouldn't have spoken so soon. My fuse blew today, I recharged it and it blew again soon afterwards. I noticed that the engine fan is on high speed when the air is on as well.

Anybody have any ideas of what could be wrong?
 
I shouldn't have spoken so soon. My fuse blew today, I recharged it and it blew again soon afterwards. I noticed that the engine fan is on high speed when the air is on as well.

Anybody have any ideas of what could be wrong?

Yes, your DCCV is shorting out.
 
How about if ac only blows out of one side of the dash. My passenger side vents aren't working.
 
How about if ac only blows out of one side of the dash. My passenger side vents aren't working.

They arent working at all? I know on mine the Dccv 1st started by killing my battery, 2nd only blew cold ac on the driver side and hot air on the passenger side and 3rd it started leaking coolant, replaced with a new one and all the problems went away.
 
Yes, your DCCV is shorting out.

Thats not what I wanted to hear! I just replaced it with a new one in December. I guess new parts can fail as well.

I might have to have it checked some where.
 
How about if ac only blows out of one side of the dash. My passenger side vents aren't working.

Do you mean that you get cooled air out of the driver's side and heated air out of the passenger side?
If so, then it's the DCCV (likely), the wiring (less likely), the passenger evap sensor (less likely), or the DATC (less likely).

Or...

Do you mean that you get no airflow out of the passenger side vents?
If so, the vents are closed. Slide the little levers beside each vent to the open position.
 
Thats not what I wanted to hear! I just replaced it with a new one in December. I guess new parts can fail as well.

I might have to have it checked some where.

Alternately (but less likely) the DCCV wiring or the AC clutch wiring could be shorting out somewhere, or the AC clutch could be shorting out.
 
Alternately (but less likely) the DCCV wiring or the AC clutch wiring could be shorting out somewhere, or the AC clutch could be shorting out.

When I recharged it, I put in about 22oz of 134a into the system. The gauge said it was really low (one that came with the 134 refill). I'm guessing a leak would cause the compressor to malfunction, blowing the fuse? I might be chasing a leak somewhere. I'm thinking out loud.
 
When I recharged it, I put in about 22oz of 134a into the system. The gauge said it was really low (one that came with the 134 refill). I'm guessing a leak would cause the compressor to malfunction, blowing the fuse? I might be chasing a leak somewhere. I'm thinking out loud.

The compressor connects to the clutch, but it doesn't affect the amount of current that the clutch coil pulls.
 
The compressor connects to the clutch, but it doesn't affect the amount of current that the clutch coil pulls.

Thanks for all of your knowledge!

Would a failing clutch coil cause the increase in the engine fan speed? As soon as the ac is turned on the fan revs up and stays at a constant high speed. It sounds like I'm about to take off on in an airplane.
 
Thanks for all of your knowledge!

Would a failing clutch coil cause the increase in the engine fan speed? As soon as the ac is turned on the fan revs up and stays at a constant high speed. It sounds like I'm about to take off on in an airplane.

The fan is supposed to go to high speed when the AC is turned on. If it's going to absolute max speed, then it might be that the AC system high side pressure is too high (too much refrigerant).
 
The fan is supposed to go to high speed when the AC is turned on. If it's going to absolute max speed, then it might be that the AC system high side pressure is too high (too much refrigerant).

The fan has been running at a constant high speed when the ac is on.

I think my best option is to take it to a shop and have them look at it. I could throw a new clutch/compressor on it but I'm not sure if that would correct the issue.

The problem first came about last fall, I replaced the DCCV in December worked good until warm weather came, fuse blew and I added some refrigerant and it worked until last week (about two months). I added more refrigerant and the fuse blew not long after.
 
I had a shop look at the system today. The guy said there was too much freon in it and causing it to have too much pressure. He vacuumed out the old freon and added the correct amounts. He said he ran it for a half hour and it ran fine. We'll see what happens over time. It seems to be fixed for now.
 
Back to the shop I go, the recharge didn't last too long.
 
I had a shop look at the system today. The guy said there was too much freon in it and causing it to have too much pressure. He vacuumed out the old freon and added the correct amounts. He said he ran it for a half hour and it ran fine. We'll see what happens over time. It seems to be fixed for now.

You say "Freon" which is the trade name for R12 refrigerant, but the LS like just about all cars from 94 on up uses R-134a which has a trade name of Suva. I assume that you are really talking about R-134a? If not, there's your problem.
 
You say "Freon" which is the trade name for R12 refrigerant, but the LS like just about all cars from 94 on up uses R-134a which has a trade name of Suva. I assume that you are really talking about R-134a? If not, there's your problem.

It was R-134a, I just never know what to call it, freon seems to roll out easier.
 
It was R-134a, I just never know what to call it, freon seems to roll out easier.

That's probably why Suva never caught on. I imagine that real Freon is very hard to get now.
 
You say "Freon" which is the trade name for R12 refrigerant, but the LS like just about all cars from 94 on up uses R-134a which has a trade name of Suva. I assume that you are really talking about R-134a? If not, there's your problem.
Most everyone calls refrigerant "Freon", just like they call wheels "rims". Neither is correct, but we all know what they are talking about. Suva is the DuPont name for it; there are other manufacturers.
 
Heard from the mechanic and he was unable to locate the problem. He was unable to get to the coil clutch to check for a short and doesn't have the tools to only change the coil clutch, they can change the whole compressor but I don't think I want that changed just yet, its a little pricey. He was going to replace the rely to see what that does.

EDIT: He looked at it some more and he is unsure where the short is and recommended me to take it to the dealer. He checked the DCCV valve for any shorts and he didn't find any there. I guess I will be taking it to the dealer for them to diagnose.
 
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