Hi,

I was working on my car and noticed the regeneration switch over valve (behind the ABS pump, with 2 vacuum lines connected at the bottom and an electrical connection at the top) making a loud noise, like something is rattling inside non stop. When I touched it I could actually feel the vibration. I don’t think I heard that before.

Is it suppose to make that noise?

I also have an issue with the heating system. The car wont blow hot air while driving on the highway. So here is what happens. I start the car and let it idle for about 10 minutes and it starts to warm up. It gets to about 60 C as the temp meter indicates. At this point luke warm air starts to blow but the fan speed is still slow as it should be. I get on the highway and start driving at about 65 + mph. The temp meter starts to go down to about 58 C and the blower fan speed slows down and the air coming in is a little cooler. As long as I am driving on the highway the temp meter never goes above 60 - 63C regardless of length of time on the highway. If I exit the highway and let the car idle eventually it reaches 80 C and even above and the heat coming is as it should be. After idling if I go back on the highway it cools down again to 60 C. I bought the car in this condition but I cannot imagine this to be normal.

So is this normal?

I have changed the aux water pump as the old one was dead but still no change. I also changed the air sampler blower motor and cleaned the temp sensor. I had put in a new thermostat about 4000 miles ago old one was stuck open but I am suspecting the thermo is failing again.

What do you guys think?

What else should I be looking into?

Any help will be appreciated greatly.

NOTE: I have removed my instrument cluster to repair the reostat and the temp gauge. I found it to be a very easy task. I have not installed it back yet. If anyone needs any picks of the back let me know. I will put it back in about 3 days when I am sure the reostat rebuild is ok.

From what you describe, it sounds like you have a thermostat stuck open and are operating the climate control in the Auto mode. If you have the blower control in the auto position, blower speed is dependent on coolant temp and heat demand. (Also vehicle speed but that's a bit more in depth than is necessary here) If you are demanding heat but the coolant is still cool, you won't get much blower airflow. Once the coolant heats up, the climate control system computer automatically (hence the "auto" mode name) increases blower speed. Once the heat demand is satisfied, the blower should slow down again.

A new thermostat is cheap and easy, if it were my car I'd try that first....

J. M. van Swaay

The ECU commands the regeneration valve to operate shortly after engine start if coolant temperature is above a certain value. It is a pulse type valve, so a slight humming or vibration is normal. I don't know if excessive noise would indicate a failing valve......

J. M. van Swaay

Thanks for the reply.

I did look at the thermostat and as I expected it is in perfect working order (did a pot test). When I was changing the thermostat last time I had lost one of the screws and could not find it. It turns out that it went in to the thermostat opening and did not allow the thermostat to close. I am so lucky that it did not get sucked in to the water pump. All is working well know. The car warms up in about 15 minutes at 17 F.

Question : What is regeneration switch over valve and what does it do?

It is loud enough that I can hear it on the drivers side with the hood closed. Is that normal?

Thanks

Regeneration valve is part of the emissions control system. Fuel tank vapors are captured and stored in a charcoal cannister. During regeneration valve operation, vapors from the charcoal cannister are drawn into the intake manifold and burned.

This valve is often referred to as a "purge" valve because it purges the fuel vapors......

You can try to spray some WD40 into the upstream side of the valve while the engine is running and the purge valve is operating--that might quiet it down a bit....

J. M. van Swaay

Thanks, I will try that.