The everlasting HVAC problem

Post by **abscate** » 19 Feb 2018, 11:52

IF the ECC control unit faults, the LEDS will flash about 15 seconds after the unit is powered up.

With a good code reader, you can actually download the fault codes which will tell you the bad parts.

Post by **scot850** » 19 Feb 2018, 12:37

The 2 servo motors that are mirrored either side of the center dash section control the amount of air and therefore the temperature to each side of the passenger compartment. The upper motor on the right of the steering column determines where the air gets directed.

As you have swapped the air sensor to the left of the fan motor, then we have to assume that is sensing the amount of cold air being sent into the car. I will assume you have checked the arm on the incoming air vent by the fan motor to confirm it is working ok. The arm can break so all it will do is let max cold air in if it is not working.

If your system is moving the air position from feet to face to windshield you can assume the motor controlling that is working also as it should.

The remaining issues will be the air mix control of the 2 motors adjusting the hot/cold mix. If the temperature when adjusted equally on both sides is not changing or they change by the same mount it only leaves 2 other options:

1) The cabin temperature sensor in the dash has failed ( have had 2 do that)
or
2) The ECC unit is bad.

If you do not have something like Vida to check the signals in the ECC system, I would suggest you find someone that can do that for you rather than through parts at it hoping it will fix it. The codes will help you/us to figure out what is going on.

One last question. Is your dashboard still good and not squeaking? I have seen the air vent get broken out when the mounts break on the dash, but usually that affects the air flow to the face/windshield most in terms of volume not temp.

Neil.

dsno · Post by **dsno** » 20 Feb 2018, 09:59

abscate wrote: ↑19 Feb 2018, 11:52 IF the ECC control unit faults, the LEDS will flash about 15 seconds after the unit is powered up.

With a good code reader, you can actually download the fault codes which will tell you the bad parts.

no flashing on the ECC. if remove any of the temp sensors it starts flashing as you say

dsno · Post by **dsno** » 20 Feb 2018, 10:05

scot850 wrote: ↑19 Feb 2018, 12:37 The 2 servo motors that are mirrored either side of the center dash section control the amount of air and therefore the temperature to each side of the passenger compartment. The upper motor on the right of the steering column determines where the air gets directed.

As you have swapped the air sensor to the left of the fan motor, then we have to assume that is sensing the amount of cold air being sent into the car. I will assume you have checked the arm on the incoming air vent by the fan motor to confirm it is working ok. The arm can break so all it will do is let max cold air in if it is not working.

If your system is moving the air position from feet to face to windshield you can assume the motor controlling that is working also as it should.

The remaining issues will be the air mix control of the 2 motors adjusting the hot/cold mix. If the temperature when adjusted equally on both sides is not changing or they change by the same mount it only leaves 2 other options:

1) The cabin temperature sensor in the dash has failed ( have had 2 do that)
or
2) The ECC unit is bad.

If you do not have something like Vida to check the signals in the ECC system, I would suggest you find someone that can do that for you rather than through parts at it hoping it will fix it. The codes will help you/us to figure out what is going on.

One last question. Is your dashboard still good and not squeaking? I have seen the air vent get broken out when the mounts break on the dash, but usually that affects the air flow to the face/windshield most in terms of volume not temp.

Neil.

to my knowledge all the servos work. the resirc "arm" sometimes hops out from the servo, but its not broken and is free to move re resirc flapper.

i've ohm'ed the cabin airtemp (the one with the fan) to be ok as pr instructions on here earlier.

my dash still seems intact. but you got me thinking there. the air volume isnt very good when air goes up to the windshield or when its going towards the occupants. it has always seemed like somthing was missing there.

however, i've bought a new fan as min is almost dead at this point..

the new fan will arrive in a couple of days. i'll give that i test and report back..

there is one thing that i just tought of. every so often it seems like the air is either escaping or hitting an obstacle within the dash somewhere. as it sounds like the air is "trapped" (if that explains it). not much volume anywhere at that point.

maybe i should investigate further next time that happens. to check if air is escaping inside the dash, could be broken, even tho it makes no sound, and is firmly held in place

Post by **scot850** » 20 Feb 2018, 11:31

Again it is a shame you are not nearer by, as I have loads of these parts we could have tried to see if they would fix the issue.

Let's see where the new fan motor goes, but I am still thinking the issue is either the ECC unit itself or the cabin temp sensor, but as yo have tested that it points toward the ECC unit.

There is a calibration process for the 98 and older if I recall, but not sure if the 99-00 can be done without Vida/Dice access.

Maybe it is time to get the car to a dealer as a diagnostic would hopefully get the answer quicker than throwing parts at it. The diagnostic shouldn't be too bad as it takes no more than about 10 minutes max to hook up, connect and read the results.

Neil.

dsno · Post by **dsno** » 21 Feb 2018, 10:15

got the new fan today. and installed it (fast and easy job this).

but still no better. got rid of the squeeling noise that the old one made. but i still don't think the flow is adequate. starts off good when car is started cold. but slowly ramps down.

is the fan only voltage regulated? with the ECC fan slider at full blast i measured 13.3v at the connector (rear probed the plug, so this is with the fan loading up the circuit).

but i still don't feel like its blowing the way it should when it heats up a bit..

starting to think it would be worth the trip to the wrecking yard to se if they might have a working ECC controller.

the dealer price is about 170us dollars an hour to have them check it out. and that is about a quarter of the value of the car. so i rather not spend the money with no guaranteed results.a few new parts is ok at this time. but not spending a minimum of 170 with no guarantee of them actually finding anything useful.

Post by **abscate** » 21 Feb 2018, 10:22

You can get a VIDA setup for about 100 EU which will help troubleshoot this.

dsno · Post by **dsno** » 21 Feb 2018, 10:58

yeah. i've seen that on the intewebz. but what i've read my car is to old to be used with vida.

and the chinese knock-offs are a bit picky on the OS version.

but would it work with my 99 D5252T?

Post by **abscate** » 21 Feb 2018, 11:10

!999 is when VIDA becomes essential, but we don't get the cool diesels here in the States

You guys are looking good in the Olympics this year, but too bad about the womens x-country yesterday

dsno · Post by **dsno** » 21 Feb 2018, 11:51

would actually make more sense to me to buy the scantool then it is to have the dealer do it

. its about the price for one hour anyways.

yeah, seems that "we've" done good this Olympic (i don't watch too much as it does not interest me at all

)

The everlasting HVAC problem

Re: The everlasting HVAC problem