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HVAC system only giving me hot air - Interior/Exterior/Lights/Glass/ICE/HVAC & Other - The Lotus Forums Jump to content
soldave

HVAC system only giving me hot air

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Might try and take a look at one of the minor issues my Eclat's had since I bought it. Should firstly state that the car has a/c, although everything in the engine bay has been removed. Not sure if that has any relevance to this, but wanted to add it for full disclosure.

My issue is that I can't get the HVAC to blow any cool air at all, even ambient cool. Moving the temperature lever to cold has absolutely no effect at all to the temperature and the only way to cool the car is to open the window! Not such a huge issue in British climes, but if I can get something working better then I'll try to do it.

I've read the factory manual and seen the rat's nest of vacuum lines that are involved in this system. And I do suspect the passenger side vacuum tank, or inbound/outbound hoses into there leak. When I bought the car the vacuum system was set up in a bit of a strange way and meant the headlamps were relying on vacuum from both driver and passenger side vacuum tanks. When I isolated the tanks and made the headlamps only rely on the driver's side, they stayed down after turning the engine off, as intended.

Is there anywhere specific I should start, or is it just a case of following the system back from the non-return valve before the vacuum tank, and testing everything until I find the leak?

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Everything in the engine bay has been removed, but I suspect that that valve is still in play behind the centre console.

Someone on FB has recommended I open up the vacuum line from the engine to the passenger side vacuum tank and see if that makes any difference. Wasn't able to warm the car up this morning but I did pull the line 24 hours after the engine had started and there was still a fair bit of air in there. Which kind of put a spanner into my thinking that there was an air leak in that vacuum tank area.

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Does your car have the early Delanair system, or the later lotus-designed one?  Not sure what year it changed.

Pete

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Allow me to correct myself: I looked under the dash today and found that my Eclat actually has the cable-operated valve and not the vacuum operated dole valve (see the awful picture below - I apologise in advance for that one!). I can also confirm that the mechanism of the valve I have does seem to move when you move the cable.

Can't answer your second point about the Delanair vs Lotus system as I don't know the differences. Sorry :(

584883938_2018-12-2809_12.55-2.jpg.ffe083ab9412ec4944e7f516b682f553.jpg

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I'm pretty sure that's the later Lotus system, not the earlier Delanair system.  Pity, because I know lots about the earlier system and not the later one!

Pete

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Just trying to do some logical thinking, and if that switch is operating in the outside, and diverts hot air into the heating system, then it must be jammed open inside, right?

Still unclear though what the passenger side vacuum system is associated with though 🤔

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Thanks John. Have had a look at that and got the engine up to running temperature this morning - couldn't drive due to being blocked in with visitors! I took a movie and the valve seems to be operating from what I can see (see YouTube link below). If something is blocked in there it's from the inside as it seems to be moving from what I can see.

I did try both hot and cold air settings and there is a difference there. When it's set to hot the air coming out of the vents is midway between warm and hot. When it's set to cold the air is... lukewarm. Not as warm as before but there is a bit of warmth in it. Wondering if it's not springing back all the way inside when set to cold air.

I also found out that the vacuum setup is responsible for directing the flow of air (either at screen, through main vents or to feet).

 

Edited by soldave

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Nice bit of movie making Dave, everything looks to be in good order mechanically, inside that valve will probably be a simple plunger with a rubber seal to divert the flow through or away from the heater, so the most likely culprit would be a perished seal. 

Before outlaying a wad of cash for a new valve it may be worth pulling this one out and having a go at a repair.

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22 hours ago, Steve V8 said:

Nice bit of movie making Dave, everything looks to be in good order mechanically, inside that valve will probably be a simple plunger with a rubber seal to divert the flow through or away from the heater, so the most likely culprit would be a perished seal. 

Before outlaying a wad of cash for a new valve it may be worth pulling this one out and having a go at a repair.

Thanks. Yeah, I might try getting some more coolant and taking it off and seeing if I can check what condition it's like inside.

Interestingly, it looks like it might be a GM part (https://www.danchuk.com/images/Downloads/Instruction Sheets/013.pdf)

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Took the car for a quick drive today with the heater set to cold air. Got back and felt both inlet and outlet pipes going to that valve and both were warm/hot. So it would look like the valve's not closing correctly.

Not a high priority issue, but I'll get some more coolant and get that valve off at some point to inspect and (if necessary) replace.

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