puzzigully

Hi guys,

Have a 1987 B2K with some minor issues, hope the collective brains trust can help.

I'm not sure of the option code, but pretty sure it's not C68 (electronic air conditioning) as the face of the heat/air cond has two levers, top one for vent position and lower one for temp control.

Assuming I'm right so far..... Here is my problem.

No matter what position the top level is in, air blows from all vents.

When it's in the A/C section, the A/C engages as it should, but air comes from all vents (windscreen, dash and floor)
Same goes for any position that the top lever is in...all the air comes from all the vents, all the time.

I'm guessing a vacuum leak?
My shop guy says it needs a new HVAC, but isn't that for the electronic control?

Any help greatly appreciated.

65Z01

Sounds like your HVAC has two slides with a rotary **** at either end.

With air blowing from all vents, sounds like a problem with the main vac line,either at the control assy under dash or at the vac line under the hood.

puzzigully

Thanks for the reply, yes it has two slides and a **** either end.

I dont have access to a vacuum diagram...could you [point me in the direction of the routing of the vacuum line?

thanks

Cliff Harris

It's highly likely that your vacuum check valve is bad. It's about $4 at any auto parts store so it's worth replacing just for the heck of it. It also supplies vacuum to the cruise control, so you might check to see if that is working. This is your guy (next to the distributor on the driver's side):

puzzigully

Thanks for that
Cruise control works fine....not sure what that means.....if anything..

Cruisinfanatic

check your vacuum lines in back of controller. Mice eat them right in half

puzzigully

You might be onto something.

There was evidence of mice in the engine bay....

Will take a look

Thanks

jv9999

Maybe this will help.

puzzigully

Thanks, that will help, is there an easy way to get at it?
Other than removing the dash from the front?

Can you get at it via the passenger side footwell etc?

puzzigully

Hi,

What's the best way to get at these?

Thanks

Cruisinfanatic

take the radio out so you can see in back

puzzigully

Guys,

Spoke to a couple of "experts" and their thoughts are that if I have cruise control, I have vacuum, therefore can't be a vacuum issue?

I've checked vacuum at the cruise control and it is there, it does work, so expected that.

What are people's thoughts on the "vacuum everywhere" theory?
Most threads show you lose both cruise control and vent control with a loss of vacuum, but not one or the other.

Cruisinfanatic

absolutely not true. My cruise has always worked fine and I had the same issue as you until I discovered mice had eaten through the vac lines from the heater controller.

Cliff Harris

All of the vacuum servos in the HVAC system are controlled by vacuum that is switched by the HVAC function lever.

This picture will give you a much better idea of how this is all hooked up. The manual (C60) HVAC control head is shown in the "View A" details: