C4ankenstein

Hey all, with the weather up here getting a little colder i was just wondering how to fix my problem. I don't drive my car in the snow but sometimes work on it and need some heat in the car, also on those early spring cold nights. The heat works in terms of blowing hot air but it is extremely weak meaning very little air comes on at the max setting on my 85. I'm wondering if there is a fix to this without checking my ducting inside the dash for leaks. Thanks

James Paradiso

If your motor is working but only at low speed no matter where you put the dial it sounds like a bad blower relay. It's located in the RH front of dash above the blower motor.

AGENT 86

There are some diagnostics in here http://members.shaw.ca/dankai/Air%20...0%20Manual.pdf

VetNutJim

I think the air has to pass thru the evaporator core even in heat mode.
The evaporator fins may be partially clogged.

dirtnapp

I have the same problem. I am going to try to take out the heater core to see if it is clogged.

Wheelman

The evaporator core is much much more likely to be the cause of your airflow problem than the heater core.

dirtnapp

this may be a dumb question but is the evaperator easier to get at than the heater core?

65Z01

If air flow is the same velocity in "heat" as on other settings it's not likely a clogged evap or heater core issue.

You might drop the hush panel to see if the blower motor changes speed with control settings. If not check out that relay mentioned.

davidf4925

blower relay is it on the outside or inside the car. pics would be helpfull if there are any. thanks

SunCr

Start by jumpering the blower directly to the battery.

raisinbran

Do you have any of these for the automatic climate control ('86)?

SunCr

For any Electronic Air, Blower speed is controlled by a Module that's mounted on the Evaporator Case. It gets low voltage input signals from either the Dash Control Panel (through '89) or Programmer ('90 and up) and the output is amplified to run the Blower. That input is allmost always a Tan or Brown wire and at Blower Speed "1", it should be about 2.5 volts; and then the output (purple or red/black or whatever is hot at the Blower) should be about 4 volts. At "10" the input is 6 volts and the output 12 volts. Check for these voltages - if this is an Input but no Output, pickup a new Module. About a $100 at any Dealer (it's used for all GM electronic a/c's) or NAPA has a stocking number. Also check the red wire at the Module - it should always be hot - and check the ground (black) which is spliced into the Blower Motor ground and terminates on the frame. Also check the Blower Motor connector. If it's discolored, it's dropping volts. Take apart the Weatherpak and solder the terminals to the wires.

James Paradiso

jimmers

If your going to go that far your might as well replace it. Its very time consuming and frustrating to get at the heater core.

94ZR1

You do realize that you are referring to the heater core with a car built around it

kittmaster

While not vette related, my achieva had this problem, the fins where so cruded up that it almost had no flow. Cleaned it out and now its crazy air flow.............good place to start if the fan can be heard spinning on high

SunCr

There's really nothing to clog up air flow to the heater core on a Vette. Air is sucked in through the screen below the windshield. On the other hand, the a/c evaporator had a foam filter attached to the inlet side at the Factory. And when the evaporator leaks, a/c oil destroys that foam and plugs it up. If you have it set to heat only, no air is directed to the Evaporator; a door is closed either manually or by an electric motor and all of the air flows to the heater core. Symptoms of a plugged evaporator would be weak air flow out of the vents, but good flow out of the heater ducts. You can verify that the door is closed by removing the resistor pod or Blower Module on the Evaporator case. If it isn't closed or doesn't move between warm (Heat) and cold (A/C), either the cable or linkage to the electric motor or the electric motor is broken.

The Vette's duct work is sealed with foam. With age it falls apart and all of the air ends up blowing out around the ECM (through '89). To seal it back up, you take off the crash pad (and anything else in the way) and wrap all of the joints with duct tape (or whatever works for you - the defroster is a bit of a challenge).

I'd still start by jumpering the blower to the battery - confirm it's got battery voltage on high - remove it and make sure the squirrel cage isn't broken and do a couple of other tests - like making sure that the leads aren't discolored and dropping volts - before tearing out the core (which often need to replaced but only because they're plugged internally - no heat at all - or leaking coolant). And of course there's always the possibility that the blower motor is simply shot.