A couple of weeks ago I pulled the radiator out of my 88 Formula and thoroughly cleaned it. Spent another couple of hours straightening the fins on the A/C radiator. Temps are down to 220 with A/C on. Really helped. But last week, a cold snap, so I went for the heat. NO HEAT. Blows cold air only even in the afternoon. Can you get a bubble in the line? What can I check to find out what's wrong?

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1988 Firebird Formula, 305 TPI, K&N filter in 'hole-y' cannister, MSD coil and wires, Accel cap, Monaco seats

 

There's some kind of diverter valve on the heater hoses you might want to check. Also you could "feel" your heater hoses to see if they're getting hot.

You said you had a K&N in a hole-y air can... which air can did you have? Was it the one with the little snorkel sticking out of the side? Or do you have the can that uses the cap as the hole to the outside world? Just making sure you're not bypassing your filter

-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.v6fbody.com mailbags

 

I still have the stock cannister with the side air snorkel. I just cut some 4 by 4 square holes in two sides of the cannister. So I shouldn't be bypassing the filter. I'll look for the valve tonight. Is it run by the computer, or is it run by the slide control cable for the heat?

 

What you are looking for is a heater control valve. Follow the heaterhoses from the heater core to a valve befor the hoce connects to the engine. check to see if it is connected correctly if so it may need to be replaced (under $30) they do go bad after several years of usage

 

Inquiring minds want to know how you found this out. It's SUMMER !

 

Inquiring minds, eh? Well, it was 85-90 degrees here in Minnesota 3 weeks ago. Then Canada decided to take a 'cold weather dump' on us two weeks ago, and when I got up, it was 49 degrees out. Car was covered with dew, since my wife insists on keeping the MGB in the garage with the top down. Anyway, I had to use the defroster, and found the no heat situation. And even last week, when she popped back up to 85, I could run the heater on full hot and enjoy the cool air on my feet. Summer stops tomorrow in Minnesota (August 1st), so I gotta get it fixed soon!!!

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1988 Firebird Formula, 305 TPI, K&N filter in 'hole-y' cannister, MSD coil and wires, Accel cap, Monaco seats

 

I would definatly check the heater control valve.It has a vacume line on the top.When you slide the selector to hot it supplies vacume to this line and opens the valve.Allowing the coolent to flow into the heater core.


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Kevin S
10.9 @ 62.87 (1/8 mile)
89 RS 2.8(bored .030)
B&M shift Improver
B&M Mega Shifter
Perma Cool trans cooler
Accel Wires,
Ignition module,
Super coil
Streetrunner chip(for now)
Flowmaster
1.52 Roller rockers

I remember learning to drive on my dad's lap. Did you guys
ever do that? He'd work the brakes. I'd work the wheel. Then
I went to take the driver's test and sat on the examiner's. I
failed the exam. But he still writes to me. That's the really
nice part.
-- Garry Shandling

 

Was just going to ask about that vacuum line. About two weeks ago, it was off the control valve, just dangling on the side. So I slid it back on, and it fits tight. That's too much of a coincidence for me, that it was off, and now I have no heat. Can the valve 'backfire' and blow that line off? How can I test that vacuum line to see if it is working?

 

Was just going to ask about that vacuum line. About two weeks ago, it was off the control valve, just dangling on the side. So I slid it back on, and it fits tight. That's too much of a coincidence for me, that it was off, and now I have no heat. Can the valve 'backfire' and blow that line off? How can I test that vacuum line to see if it is working?