DCCV linked to overheating?

[sowberry]

Hi all. 2002 V6 101k miles. I think my DCCV is finally dead. When A/C started not blowing cold in the summer several (at least 10) years ago, I got by doing the turn temp all the way down to 60 trick. This trick stopped working last summer (just kept climate control off).

A couple months ago (winter, still cold), I had been sporadically getting some kind of code beeping on start (happened more regularly if engine was warm). It was a 5-5 sequence, so it's not because my airbag light burned out (still get the 3-6 flash). Then I got my first overheat (gauge a little over 3/4). DATC on auto 70, A/C off. So I decided to check the oil. It was low, and adding some seemed to kill the beeping (don't know why there's not just an oil warning light). Next start, the temp gauge seemed to jump immediately (bad thermostat?), but temp stayed normal.

No more problems (temp gauge doesn't move for several minutes after cold start, stays normal) until yesterday, first time trying A/C this year. DATC 60, blew cold for a few minutes, then warm both sides; passenger seemed colder last summer, which makes me think DCCV finally failed. Few minutes later, temp gauge again goes over 3/4. Turn off A/C and crank DATC to 90, gauge goes right back down a little above normal (hot air thru vents). Luckily was close to home, but was in the middle of something, so just switched cars and didn't get a chance to look under the hood.

Could DCCV be related to the overheating? Like coolant is low, but cranking the heat somehow bypass the DCCV so there's enough to flow? I do sometimes smell burning coolant, but I don't see any white residue. Coolant level is low, so there is leak somewhere. So I guess I need to replace all the plastic. Made it 100k, so better than some. But will replacing the DCCV get my climate working?

 

[joegr]

Your main issue is that same as everyone else. Replace all the plastic cooling system parts now, including the DCCV.
The 5-5 beep is an SRS fault and not related to anything else.
You should check your oil level periodically and not let it run low - still not related to the beeping or overheating.
The LS does have a low/no oil pressure light. Very few cars (BMW and recent Jaguars being the exception here) have monitoring for low oil level.

 

[sowberry]

Thanks for the response joegr (sorry about another overheat thread ).

Interesting that the 5-5 beep is SRS. The 3-6 airbag light flash is the broken wire under the seat. What does the beep mean?

I topped off degas this morning with the engine cold and drove about 2 hours today mix of highway/local. No abnormal temp gauge movement. Anyways, I realize I will run the risk of overheat while there is coolant leak (possibility of air getting sucked in during cooldown). But most of my driving with the LS is 20-30 min trips (minimal overheat risk). So my question was more whether I could at least restore climate function by replacing DCCV first, i.e. will replacing give me A/C before I commit to doing the whole system replace?

 

[Blueberryyum02]

Hi all. 2002 V6 101k miles. I think my DCCV is finally dead. When A/C started not blowing cold in the summer several (at least 10) years ago, I got by doing the turn temp all the way down to 60 trick. This trick stopped working last summer (just kept climate control off).

A couple months ago (winter, still cold), I had been sporadically getting some kind of code beeping on start (happened more regularly if engine was warm). It was a 5-5 sequence, so it's not because my airbag light burned out (still get the 3-6 flash). Then I got my first overheat (gauge a little over 3/4). DATC on auto 70, A/C off. So I decided to check the oil. It was low, and adding some seemed to kill the beeping (don't know why there's not just an oil warning light). Next start, the temp gauge seemed to jump immediately (bad thermostat?), but temp stayed normal.

No more problems (temp gauge doesn't move for several minutes after cold start, stays normal) until yesterday, first time trying A/C this year. DATC 60, blew cold for a few minutes, then warm both sides; passenger seemed colder last summer, which makes me think DCCV finally failed. Few minutes later, temp gauge again goes over 3/4. Turn off A/C and crank DATC to 90, gauge goes right back down a little above normal (hot air thru vents). Luckily was close to home, but was in the middle of something, so just switched cars and didn't get a chance to look under the hood.

Could DCCV be related to the overheating? Like coolant is low, but cranking the heat somehow bypass the DCCV so there's enough to flow? I do sometimes smell burning coolant, but I don't see any white residue. Coolant level is low, so there is leak somewhere. So I guess I need to replace all the plastic. Made it 100k, so better than some. But will replacing the DCCV get my climate working?

Check to make sure your airbag light comes on and goes off when mines did the beeps on start up it was the airbag bulb in the instrument cluster that had blown out

 

[04_Sport_LS]

When overheating... can you hear the cooling fan run?

Does the cooling fan come on when (trying) to use the A/C?

 

[sowberry]

The degas sh*t the bed soon after my last post (big puddle), so I ordered a new one and a DCCV to go with (both OEM).

No issues replacing degas other than having to cut one of the hoses off. There was some kind of corrosion or something on the aluminum tube so that there was some caked deposit under the hose. I could not get it to twist and break free, so I cut it since the new degas came with the hose anyways.

The DCCV is another story. Already spent prolly 8-9 hrs trying to work in that tiny space fighting with the hoses. For future reference, absolutely essential tool was a 15-in long reach locking pliers for the spring clamps.

I saw someone else advise against detaching the QCs (quick connects) because the plastic can get brittle and break, but I think it would be literally impossible to remove the DCCV without detaching the QCs unless you took out the radiator for room. As it is, I had to take the old DCCV out from the bottom because I couldn't get it past the EGR.

Anyways, the QCs worked fine when detaching even though they're 20+ years old. I've now got the new DCCV in with all the hoses attached to it (recommend replacing spring clamps with regular worm drives for the non-QC hoses; easier to install), but I have a question about reconnecting the QCs I hope someone here can answer.

After removal, I noticed one of the aluminum tubes had a rubber O-ring on it, but the other didn't (since the bottom one has a different, i.e. 90 degree QC, I'm not including it in the comparison). So I looked around and sure enough found on the ground 2 O-rings and what looks like a plastic spacer (same size as O-ring). I looked inside the QCs, and one still had an O-ring in it, so there are 4 total. I'm guessing both QCs are both supposed to have one on the tube and one in the QC (goes against the end of the tube). No idea where the spacer came from. Anyone know how they are installed?

 

[04_Sport_LS]

I never messed with the quick connects when replacing the DCCV.

I figured that would cause another leak point (if it aint broke, dont mess with it).

While the spring clamps are a pain, they do actually work better than "screw drive" clamps.