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1998 Passat VR5 Syncro
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32 Posts
Discussion Starter · #1 · (Edited)
Hello!

We have a problem here, that there is only cool air coming out of the vents, even when the Climatronic is set to HI and engine is hot.

So far the car got replaced thermostat, then pump and finally heater core, because we thought that there is a problem with the cooling system. And probably there was one after all, because I was the one to replace the heater core and when I was removing hoses from heater core pipes, there was no antifreeze in them.

Anyway... Now everything is tested, cooling system is perfectly fine, heater core pipes are hot as hell, but still no hot air. Actually on very rare occasions there is slightly warm air coming out of the vents, but after a minute or two it gets completely cold again. And it's not related to engine revs.

So my next guess would be the air distribution box or whatever it's called... Connected to HVAC through VCDS, no fault codes stored. Checked flap positions through Meas. Blocks, all the numbers move as they should. All the temperatures were realistic as well. Tried to calibrate the flaps through Basic Settings, still no errors or anything, that would indicate a problem...

Could it be, that the heat adjustment flaps have some how broke off and don't move anymore? But the suspicious thing is, that the car has two zone Climatronic system and both zones don't have heat. As far as I am understanding, there are separate flaps, that adjust heat to each side. What are the odds that they both have failed at the same time?

Any ideas where to look at, before dismantling half of the car to get to the air distribution box?

P.S. The car is a Seat, but as far as I know, Climatronic is the same as on Mk5 Golf.
 

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1998 Passat VR5 Syncro
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32 Posts
Discussion Starter · #2 ·
馃啒

The car will be by me on Saturday again. Seriously nobody has no idea what to look for? 馃ザ
 

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Maybe look for... a new car? Sorry, j/k. It's hard to help now that you have checked all the obvious things already.

I'm stuck thinking about how the first time you pulled the heater core, it had no coolant in it. So the heater core hoses are hot as hell - in the engine bay? I would get under the dash and make sure the heater core is also hot. Because if it is, you should have heat. Can you get to the flaps, and see if they are actually allowing air to pass over the core?
 

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1998 Passat VR5 Syncro
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32 Posts
Discussion Starter · #4 ·
That was my suggestion to the owner as well (it's my neighbour's car) - wait for the summer and sell it 馃榿

It had some coolant in the core itself but not in the hoses. My guess is that hoses drained during pump replacement and air couldn't be bled out because old heater core was clogged..

I did not touch the core itself but the pipes right before it, under the dash. (Mk5 heater core is located by driver's feet and the system consists of hoses coming at the firewall from engine and then there are aluminium pipes going under the dash from firewall straight to the core.)

About the access to the flaps - I have no idea. I guess that it is possible only by taking the whole dash apart and that's what I am trying to avoid right now...
 

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Hello!

We have a problem here, that there is only cool air coming out of the vents, even when the Climatronic is set to HI and engine is hot.

So far the car got replaced thermostat, then pump and finally heater core, because we thought that there is a problem with the cooling system. And probably there was one after all, because I was the one to replace the heater core and when I was removing hoses from heater core pipes, there was no antifreeze in them.

Anyway... Now everything is tested, cooling system is perfectly fine, heater core pipes are hot as hell, but still no hot air. Actually on very rare occasions there is slightly warm air coming out of the vents, but after a minute or two it gets completely cold again. And it's not related to engine revs.

So my next guess would be the air distribution box or whatever it's called... Connected to HVAC through VCDS, no fault codes stored. Checked flap positions through Meas. Blocks, all the numbers move as they should. All the temperatures were realistic as well. Tried to calibrate the flaps through Basic Settings, still no errors or anything, that would indicate a problem...

Could it be, that the heat adjustment flaps have some how broke off and don't move anymore? But the suspicious thing is, that the car has two zone Climatronic system and both zones don't have heat. As far as I am understanding, there are separate flaps, that adjust heat to each side. What are the odds that they both have failed at the same time?

Any ideas where to look at, before dismantling half of the car to get to the air distribution box?

P.S. The car is a Seat, but as far as I know, Climatronic is the same as on Mk5 Golf.
So no heat from any of the vents from any position, floor ,dash, windshield?
 

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I have seen Hvac issues when a sensor is not reading correctly but I can not imagine they all are not working, and yes you have two flaps for heat control by 2 different motors so that would be strange to have both fail at the same time. Have you used the secret climatronic menu to do diagnostics on the system and see if it brings up something Vcds did not? Do all the various temp sensor in the system show a realistic reading based on the air temp? When you installed the heater core did you use a coolant refill air purge tool, this is the preferred method to do it on a VW not sure what Seat asks for but you might try to rule out air block in the system.
 

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1998 Passat VR5 Syncro
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Discussion Starter · #8 ·
I have seen Hvac issues when a sensor is not reading correctly but I can not imagine they all are not working, and yes you have two flaps for heat control by 2 different motors so that would be strange to have both fail at the same time. Have you used the secret climatronic menu to do diagnostics on the system and see if it brings up something Vcds did not? Do all the various temp sensor in the system show a realistic reading based on the air temp? When you installed the heater core did you use a coolant refill air purge tool, this is the preferred method to do it on a VW not sure what Seat asks for but you might try to rule out air block in the system.
I already have done it all and everything was ok. But the important thing is, that today I got to the real problem. It's just my stupidity. So when I installed the new core I didn't pay attention to the fact, that the replacement core didn't have this seal. I thought it would be no big deal if maybe like 10% of air would be blown past it. But it turned out to be a big deal. Luckily I had some leftover rubber window seal (for house windows, self adhesive), I squeezed it in there as good as possible without taking the core out and we have heat again 馃榿

Rectangle Automotive lighting Gas Musical instrument accessory Electric blue


So thanks everyone for trying to help! (y)
 

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1998 Passat VR5 Syncro
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Discussion Starter · #10 ·
Ok, so I did celebrate too early. Today received a message that heat is gone again. Seriously I don't know what to do at this point.

After the "repair" heating operated perfectly. Clima set to Auto 22掳C and stable heat coming out of all the vents. And two days apart we are again where we started...
 

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ARRrrg! That sucks. I got all happy for you. Then read the latest post. Climatronic.... I never trust digital heating systems. I know, it's like every single new car now. But older systems in german cars.... sketchy.
 

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Did your core have seal B installed already and not seal A or were they both missing and you just did seal A?
 

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1998 Passat VR5 Syncro
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32 Posts
Discussion Starter · #14 ·
Did your core have seal B installed already and not seal A or were they both missing and you just did seal A?
Seal B was included. And it looked just like the original one, so there couldn't be a problem with that.
 
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