How to: 2nd Gen NO AC ( or heat) FROM VENTS!!! A "How to" what to look for thread

[stakreutemazda]

I think vacuum is always present at the white line. Vacuum is switched to the grey line when cold temp is selected. does this help?

edit. if you have an EATC control unit, there are well known vacuum issues associated to it not covered in this thread. Usually it requires a very tedious rebuild, or, replacement.

I got a little too detailed with my posts, sorry, but I'm about deaf so Ican't hear those "doors" working,and I need a second person to watch the vacuum working the diaphragms. Thats why this is all written out. It's asking a lot but unless we are on the phone it's the best I got. Thanks for all the input, believe it or not I've come away with some answers, bad news is I have a couple of more questions.LOL

 

[F Stiteler]

Info added-
Boy-I like my AC !

Now I need to get a new center vent. Mine is weird--

I just had brakes and rotors replaced. Any chance issued caused during that maintenance?

 

[Turdle]

I just had brakes and rotors replaced. Any chance issued caused during that maintenance?

Check for the plastic vacuum lines above the passenger side inner fender. If by chance they tied a wire to hang calipers, I could see one line becoming disconnected or broken. Might have bumped into exhaust manifold causing a melted clog , or burned into two pieces.

 

[JOC]

Great post, very helpfull. I just start with that problem, never imagine such a system. Thanks a lot.

 

[JOC]

Great post, very helpfull. I just start with that problem, never imagine such a system. Thanks a lot.

 

[Judgetodd]

There you go,
As you can see there are several places to develop a leak-from loose lines hitting the exhaust to a broken globe, or even a leaking contol switch.
Not to mention about 50 connections--
If there is the slightest leak-the diaphragm motor in above post will not "close" and all the air will blow from the defrost ducting--

Now, about the other lines--

The red, blue and yellow lines work to control "blending" of the vents-floor and defrost only. (Don't confuse this with the dreaded hot to cold "blend door")
These colored lines will not usually be a problem--

OK

Your mission, find the vacuum leak.
Mine turned out to be the connection inside the firewall right above the fuel pump inertia switch-it was kicked loose.

For the first time in over a year, I now have ac from the vents!!!!

I have a question??? What would cause this problem randomly??? I bought a 2000 last May and had the heater core replaced a ac charged and everything has been great until the past few trips pulling the boat to the lake. On the Auto setting it seems to come and go thru the main vents????

 

[239]

I have a question??? What would cause this problem randomly??? I bought a 2000 last May and had the heater core replaced a ac charged and everything has been great until the past few trips pulling the boat to the lake. On the Auto setting it seems to come and go thru the main vents????

I have a question??? What would cause this problem randomly??? I bought a 2000 last May and had the heater core replaced a ac charged and everything has been great until the past few trips pulling the boat to the lake. On the Auto setting it seems to come and go thru the main vents????

I was only getting airflow through the defrost vents on my 2000 because the grey vacuum line that connects to the heater control valve broke down by the blower motor. I bought 1/8” inner diameter silicone vacuum line and connected it to the broken stock vacuum line, and then connected it to the heater control valve. The silicone hose slides over the stock grey line and the heater control valve port. I also covered what was left of the stock grey vacuum line with 3/8” wire conduit all the way down under the blower motor to protect the line from further heat damage.

 

[Judgetodd]

I was only getting airflow through the defrost vents on my 2000 because the grey vacuum line that connects to the heater control valve broke down by the blower motor. I bought 1/8” inner diameter silicone vacuum line and connected it to the broken stock vacuum line, and then connected it to the heater control valve. The silicone hose slides over the stock grey line and the heater control valve port. I also covered what was left of the stock grey vacuum line with 3/8” wire conduit all the way down under the blower motor to protect the line from further heat damage.

View attachment 450935

I was only getting airflow through the defrost vents on my 2000 because the grey vacuum line that connects to the heater control valve broke down by the blower motor. I bought 1/8” inner diameter silicone vacuum line and connected it to the broken stock vacuum line, and then connected it to the heater control valve. The silicone hose slides over the stock grey line and the heater control valve port. I also covered what was left of the stock grey vacuum line with 3/8” wire conduit all the way down under the blower motor to protect the line from further heat damage.

View attachment 450935

10-4 I’m going to have to investigate this!! Just started recently