Why is the ventiation system blowing HOT air only?

Hoping that someone here can clue me in on what is happening with my Golf.

Driving along the other day I suddenly noticed that the cabin was getting very warm - it was set to blow cold, and I had already been underway for about an hour when it happened.

Turning on the AC does nothing, it just keeps blowing very hot air.

Coolant level is normal, temp gauge is at normal level and engine also appears to be at normal temperature when checking under the hood.

Any ideas

Telling us which car may help down the road. Do a little more digging. It could be the air mix door broke or the AC system isn't happy.
Interweb guessing you'll get right to the AC, it's a whole family of components.
DanG144 has put together a nice troubleshooting guide at-
Check your radiator/condenser fan operation NOW

BobnOH said:

Telling us which car may help down the road. Do a little more digging. It could be the air mix door broke or the AC system isn't happy.
Interweb guessing you'll get right to the AC, it's a whole family of components.
DanG144 has put together a nice troubleshooting guide at-
Check your radiator/condenser fan operation NOW

Click to expand...

It is a year 2000, Golf TDI.

That thread/sticky is everything you could hope for troubleshooting your A/C issues. I used it for my car when I had problems.

... but since it's blowing hot air (rather than a lack of cold air) the most likely suspect is a blend door issue... most likely, the foam on the blend door has deteriorated over the years and is now letting hot air from the heater core into the cabin even with the "Heat" knob turned to Cold.

"Blend door" as a search term should bring up a whack of threads on what's happened and your options to fix it.

If in fact the issue is hot air, rather than "no cold air from my A/C".

And when Dan's around (he travels) he's real good about answer every little repeat question. Guessing some skip over it because the title says "fans". It's pretty complete, especially for the core years/models.

Check the cable and the pivot point at the bottom of the HVAC case were the temp cable attaches.

When the foam goes, you get no heat. That is clearly NOT your problem.

oilhammer said:

Check the cable and the pivot point at the bottom of the HVAC case were the temp cable attaches.
When the foam goes, you get no heat. That is clearly NOT your problem.

Click to expand...

You are right, it was the pivot. Easy fix. Thank you!

If that pivot fell out of the airbox it'll do it again; it's worn out and won't stay in place. CoolAirVW (here) has a nice replacement part for that which will fix it at a reasonable price (VW has disco'd the OEM one -- how nice of them!)

It is included with the new HVAC case, which I find these need more often than the little pivot alone breaks. Which I have NEVER seen.. but was alerted to it from Richard telling me about the piece he has, which is the only way I was able to guess as to the solution to the OP's problem.

Resurrecting an old thread, but I've had similar issues in the past that have reared their ugly head this week.

'03 Jetta TDI. The pivot has fallen out of my airbox 2-3 times over the years, and I've learned that it's an easy fix. Stand on my head, reach in through the driver's side and pop that sucker back in.

Earlier this week it popped out again, evidenced by a HOT commute home on Monday. (It's cool in the mornings here still so it's not noticeable on way to work.) When I got home, sure enough, it was out and I put it back.

Tuesday, cabin was hot again on the way home. Checked pivot and it was in place. Hmm.

Same thing yesterday. Hot on the way home. I checked the pivot again and it was in place. I popped it out, moved the dial back and forth while holding the pivot to see if by chance it wasn't clocked correctly. Best I can tell, it is keyed to only fit one way. Popped it back in and went on with my evening.

Well this morning I had NO HEAT. No matter what I did with the dial, it was freezing in my car.

Question is this: Can the pivot be inserted incorrectly?

If the pivot is not pushed in all the way, or with as many times as you have popped it back in the thin aluminum tab that fits into the pivot could be bent and so it’s not moving the door any more.

If your pin keeps popping out the small plastic taps on the side of the pin that keep it in place have broken off. Get one of coolairvw’s or find one on eBay and with an inspection mirror check on the tab it should be sticking well down into the sleeve the pin fits in. It may just have gotten pushed up into the air box in which case you might be able to move it back in place with your finger or a small short screwdriver.

If the tab has been bent I was able to straighten my daughters with a pair of 90* long reach pliers.

Tab was bent over. Man what a bugger to get to.

Thanks Tdijarhead.