Do you know about the secret setting between defrost and interior? Heat only comes out the windshiled vents when on defrost, but you can get heat out of the other vents if you are somewhere about 2/3 of the way between defrost and interior.

the other issue is when the vacuum supply to the controls in the dash isn't working, and doest divert the hot water to the heater core. Check you vacuum to the controls under the stereo.

 

...when the vacuum supply to the controls in the dash isn't working, and doesn't divert the hot water to the heater core. Check your vacuum to the controls under the stereo.

The other common problem is when the plunger "tip" on the HVAC cam followers is missing. Then the controls will not move far enough to turn on the heat.

+++++

If your Esprit was previously owned by someone in a warm climate (or used only during sunny days) you may have a clogged (from disuse) heater matrix. Get back to us if you think this is the case. And, use the heater periodically...just to keep it working.

 

Get the motor up to operating temperature and feel the hoses by the heater core. If they are not hot there are only a few possibilities;
Heater valve stuck closed
Hoses or heater core plugged up
Heater core and hoses not connected because the core leaks.
Coolant level very low because of leaks and air in the cooling system
David Teitelbaum

 

Will take a look at a few things tomorrow and post an update, thanks for all the suggestions.

I've tried various vent settings with the heat control all the way to the hot setting, does not seem to blow any hot air.

Car was cleveland-based in a past life, so being a colder climate, would have assumed heat was used. But was a known issue when I purchased recently.

I don't suspect any leaks. I had all fluids replaced recently, all up fully topped up, no smell of coolant leaks or any signs of any leaks at all.

Where is heater valve located?

I think I can check vacuum lines, I'll pull the stereo and see what hidden back there.

I'll feel lines for heat, but I don't think there will be, my brother checked when we bought the car, he didn't think the coolant was circulating to the core.

Will post update tomorrow evening...

 

Where is heater valve located?

It is up under the dash, just left of center.

If you remove the fusebox from the front luggage compartment you can JUST see it through the hole... :huh:


:UK:

 

It's probably the vacuum. It's happened on both Esprits that I've owned. If the vacuum is working you should hear a clunk when you move the defrost to the opposite position (floor heat).
On my SE it was a faulty line by the mechanical pump. On my S4 it was a bad connection on the electric pump.

 

I let the engine warm up, felt around behind dash wherever I could, didn't feel any warm pipes.

I think when I get a chance I'll pull the radio out and see if any vacuum lines are disconnected or leaking. After that it may be part inspection/fix/replacement time if any parts seem easy to access. After that, wait for warmer weather!

 

Heat update

OK, big update, not solved but much better diagnosed:

Heat works, I can feel a trickle of heat out of the defrost vents, pipes nice and hot. But no air blows out of the defrost or floor vents. All air (and cold) blows from the dash & knee vents. I had to turn the side vents off and rotate the knee vents to as closed as I could then I felt a wisp warm heat from the defrost vent, but barely any air flow.

So, looks like some mechanical item is not moving a flap somewhere. The control on the right seems to do something when it goes from normal to max cold, I'm guessing recirculate air at the max setting, but it does seem to be working. The temperature control on the left does move the cable, I traced it all the way to where it goes into the box way up under the dash and I can feel movement like the cable is working.

So whats next to fix? Is this end up being a vacuum control to move the flap? The dials seem to be moving the appropriate mechanical parts.

 

1990 SE

I am having the same issue with my Esprit. Just a trickle of heat from the defogger and below. Where are the cams followers for the hvac located ? thanks for all you help.

 

Where are the cams followers for the hvac located ? .

They are located behind the HVAC panel. Might be able to catch a glimpse from underneath on the passenger side. If not, remove the radio.

If/When you access the cams and actuators, push them in to see if the air-mix or directional (mode) flaps move. If not you have a vacuum problem.

Good diagram in Section PD: page 4 of the Lotus Service Notes (S4 - V8). Shows the "dryer hoses", vacuum diagrams, and controls (even the little actuators on the ends of the control cam rods)

 

Update: Heat is fixed!!!

Heat is fixed! I was able to locate the problem. One of the two solenoid plungers was not properly activating when the defrost control was being adjusted. Pic attached (hopefully) shows the two solenoids that route vacuum to the appropriate HVAC flaps. I had no air blowing out of the floor or defrost vents, a simple adjustment of this part allowed the plunger to be pressed in thus causing hot air to flow once again from the defrost and floor! I also noticed that the flow is much decreased through the two knee vents when defrost is selected, so its better than I had planned.

Once I assumed the 'lotus position', I could clearly see the plunger (1) not moving when the control arm was twisted, it had simply slipped about 2mm in its mount. A small phillips screw driver was used to loosen the mount, then the vacuum solenoid could be adjusted, and the mount re tightened. The other solenoid (2) shown was operating fine.

Now on to the 'fan failed' and horn issues...

Happy New Year!