HVAC: No air from any vents

[chrisshara]

Blower motor is blowing. Not getting any air from any of the vents. I would imagine something is blocking airflow just past the blower motor. But I just wanted to put this out there to see if anyone has encountered this and maybe correct my train of thought. Thank you for your time.

[Legacy777]

Do you feel anything coming near your feet?

I would first suggest having someone press the different HVAC buttons while you look at the levers on the air duct box. The plastic levers can be seen from the driver's side footwell area. If they don't move, the HVAC control unit solder joints may be bad, and you can resolder them.

http://bbs.legacycentral.org/viewtopic.php?f=10&t=1142

[chrisshara]

Thanks Josh. I'll let you know what I do find.

The following morning, when I left my house for work, I was getting air flow again. I do know that my A/C evaporator does like to ice over. And we're back to the cold season here in CT. So, it might have been my evaporator that iced over. I did have the front defroster on, at the time. Time to unplug the A/C compressor for the season, until I find time to replace the expansion valve / office tube.

[Alphius]

Yep, I think you nailed it. Iced the evaporator over. Your Evap temp switch is probably either defective or bypassed.

[Legacy777]

Yeah, I agree with Alphius you should look at replacing the temp switch or verifying its operation.

[chrisshara]

Thank you for the help guys. Is this sensor attached to the evaporator ? I may be getting a little off the subject here. Would this sensor being fault also cause the A/C compressor to cycle on and off like crazy ? I can hear a relay clicking on and off like 20 times a minute. It sounds like this relay is located in my passenger kick panel. Only happens when I'm using the A/C. So I' not sure if it's a fan relay or the A/C compressor relay. And it is intermittent.

[Alphius]

Yes, the evap temp switch is attached to the backside of the evaporator. It requires dash removal and A/C evac and recharge to replace. Yes, it also causes that clicky relay problem sometimes when it fails.

[chrisshara]

Thanks for clearing this up for me, Alphius. While I'm in this deep, is there any other common components to "refresh" while I have this all apart ? Or is this the only component that commonly (or uncommonly) fails that requires dash removal ?

[Alphius]

The heater core is worth doing while it is all apart if your car is anywhere near or over 200k miles or so. I've had two heater core failures in different cars, one at around 260k and one at about 275k. Maybe coincidentally or maybe not, both of these failures occured after a significant overheating event due to bad headgaskets, in both cars. One had a bad headgasket 30k before and the other had a HG failure barely 10k before. Regardless, if you have the dash apart that far and plan to keep the car for a very long time I personally would replace the heater core if the car had any significant mileage.

A parts store heater core wouldn't fit in the heater box for me, it is too thick. I tried four different parts stores and all had the same problem so I just purchased it directly from Subaru eventally. OEM is the way to go and it is quite expensive at nearly $300 last time I bought one.

If I remember correctly the Evap Temp Switch is nearly $100 from a dealer.

[Legacy777]

Just an FYI, you don't need to remove the dash to get the evaporator box out. All you need to do is remove the glove box and the lower support bar for the glove box (6 screws) and then there is a nut and bolt at the top and bottom of the evaporator box that will allow it to come out. I've had mine out many times without taking the dash apart. However, as Allphius mentioned, it will require discharging and recharging the refrigerant.

You can see the evap box and various components in some of these pics.

http://www.main.experiencetherave.com/s ... es/accomp/


Also, some folks have bought a new temp switch unit (which bolts to the top of the evap box and can be accessed without removing the dash or evap box) and spliced the wires from the old thermister in the evap box to the new temp switch controller. Since it's a temp sensor, it shouldn't matter which wires are wired to which, but I'd try and wire them the same.

[chrisshara]

My car has 310,000 miles on it. I have not done the heater core yet. I bought the car in 2006 with 189,000 miles on it. I'm on my second timing belt / w-pump. Ok, so I can replace the evaporator temp sensor without removing the dash. Just yank the evap box directly behind the glove box. I called my friend who is a parts manager at Subaru. He's no good with the older EPC diagrams and was not able to find the evaporator temp sensor for me. Would either of you happen to know the part number ? I think I inquired about a heater core from Subaru, and I think they were discontinued. I was going to pick one up, to have it on hand. Does the dash have to be removed to replace the heater core ? Or is it also located in the evap. box ?

[chrisshara]

….Just checked out the pictures. Looks like the heater core isn't in the evap box.

[Legacy777]

Yeah the heater core is separate.

As for the part #, check out this post & thread.

http://bbs.legacycentral.org/viewtopic. ... 13#p410213

[chrisshara]

Ok, the evaporator thermostatic switch is on order. FYI, I was told there are only (8) left. I'm not sure if that means there is only (8) left in the country, or only (8) left in a given warehouse, or (8) left in the world and when they are gone, THEY'RE GONE. And I paid $119.08 plus tax for the thermostatic switch.

[Legacy777]

Ok, let us know when you get it and get it installed.