Heater surges air in car...

AlanS · Post by **AlanS** » 02 Feb 2016, 18:26

2001 S40. When the heater/ a-c fan is on any #, it will periodically surge. You can feel the air through the dash vents, and then, unexpectedly, there will be a surge of air...Almost like it's on Auto climate and it's trying to reach a certain temp. very annoying. I have no idea how to attack this problem.

Post by **alschnertz** » 03 Feb 2016, 03:30

My '01 does the exact same thing. Has for 2-3 years now.
I've noticed that the only time it doesn't surge is when set to "0" or "4". That's off or full-blast which really aren't great options.

I think I read (years ago) that it's a symptom of the ECC failing (big surprise). I don't remember what the repair was other than replace the entire ECC. I suspect there is something as simple as a resistor or something like that that is burned out or has a bad solder joint. I haven't pulled mine apart yet.

With no evidence, I've also blamed it on the idiotic location of the cup holder. Though I've never used it, I can see that the previous owner had soda spill into the sensor that is right near the cup holder.

Post by **alschnertz** » 23 Apr 2016, 15:11

I changed the blower transistor today. 7 bucks.
We'll see if it works properly now.

Kdad · Post by **Kdad** » 28 Apr 2016, 19:59

Did your fix work I'm having the same issue.

Post by **alschnertz** » 01 May 2016, 11:33

I'm not sure yet.
The first time I turned on the fan, it seems as though it surged once or twice and then stayed at a constant speed.
I rarely use the fan in my regular driving, so I can't be exactly sure yet.
I'll experiment more this week.

Post by **alschnertz** » 13 May 2016, 14:53

It seems better, but I'm not convinced that that was the problem.
On "AUTO" the speed is pretty consistent. Maybe an occasional burst.

When just venting with no A/C and the blower, it has surged a few times.
I'm going to start jiggling the blower switch. That seems suspect to me now.