MA61 + 1JZ + Heater problems

[thechuckster]

I think you missunderstand how the MA61 climate control works...

when you turn on the climate control and the coolant is over 50 degrees the heater core gets hot water. The fan blows air (chilled or not) thru the core and also bypasses it - the temp in the cabin is controlled by mixing varying amounts of hot & cold air. The vacuum-operated vane is the thing that mixes the two airflows.

If there's no coolant going to the heater core, the climate system only blows cool. If those two sensors on the tap don't see hot water, the climate system wont attempt to mix/direct air from the heater core as it thinks there is no hot water in the core.

The system is analog and uses electrically valved vacuum actuators to shift things around (like the air mixing vane) - so you have to consider that and electrical fault may present itself as a non-operating actuator.

[Gibbon]

Ok - but isn't it the water tap and the two sensors in that tap, that decide if hot water will enter the core or not?

If there is no heater tap (bypassed) - then the core should always have hot water in it (as I have the engine hoses connected directly to the core.

But, from what your saying, it could be the vacuum operated vane that is not working - it seems to be always on cold ( or bypass the core ).

I've got most of the dash out - all the mechanical bits are working. Which area should I look in for the vacuum operated vane?

[Gibbon]

I've had another thought.

Assuming that the heater core is full of hot water; and assuming the electrics are ok; Could the problem be that the whole system was connected to boost not vacuum (as suggested by Charles) during the conversion.

Would that stop the vacuum operated hot air / cold air vane from operating ? Resulting in only cold air being blown.

I've been for a drive with the center console sensor disconnected, which before the conversion, resulted in hot air all the time.

If thats the case, where does the vacuum for the heater system come through the firewall to connect to the engine? Same hole as the wiring loom??

[thechuckster]

vacuum from rear of manifold goes (via 1-way valve that you'll need as the factory system was designed for a NA motor) to a vacuum reservoir mounted on the chassis rail below the heater tap then onto various thingsl ike the interior and the VSV valve that controls the heater tap.

[Gibbon]

vacuum from rear of manifold goes (via 1-way valve that you'll need as the factory system was designed for a NA motor)

Are you saying even if the climate control system is working perfectly before a conversion, it's not going to function unless there is a 1-way valve installed as part of the conversion

[thechuckster]

is pretty obvious - a vacuum system isn't designed to see boost.

[Gibbon]

Ok - A little progress.

It's the DVV that controls the vane that mixes hot and cold air - disconnected the rod and used it to manually move the vane - all good - I can now get hot air into the car.

The DVV seems to be working - I can suck air through the vacuum connector and the vacuum moves the slider arm that is connected to the rod that is connected to the vane.

However, there is no vacuum coming from the tube to the DVV ( at least holding my finger over the end tells me there is no vacuum ).

As thechuckster has been pointing out - the MA61 heater system is not supposed to run from a 1J engine.

Now, assuming I can find the vacuum tube that connects the heater system to the engine - where is a good spot to tap into a vacuum line?

Is the brake booster a vacuum line? I also have cruise control installed and working - would I be right in thinking that it is vacuum run as well.

If none of those work - what sort of 1-way valve do I need to get?

Thanks.

[wilbo666]

There is a little vac reserve canister that operates the heater valve (Via a VSV or two?). It is usually located a little bit under the valve its self

You can trace its vac line back to the manifold and a put a one way valve in line with the vac hose it uses!

Cheers
Wilbo

[Gibbon]

Information I could have used BEFORE I removed the entire dash

Anyway - now I know exactly how the heating system is supposed to work. Autobarn have a generic PVC one way valve for $10 - I'll give that a go.

[wilbo666]

no no....it is in the engine bay!

There should be a little vac canister in the engine bay under where the heater valve usually is. I think this is the vac reservoir for the climate control.

Cheers
Wilbo

[Gibbon]

Yes - I know that now !

I've had the dash out trying to track down the problem. I know exactly where the canister is, I've been tracing those hoses as part of the problem finding.

My point was, all I needed to know was that I had to have a one way valve in order for the heater to work properly.

It's taken me two days, and the removal of the dash to have found out that little gem of information

[ma61turbo]

I'm going to jump in here rather than starting my own thread(sorry!!)

My heater system failed last year around the time I was having major cooling issues with the car. It has always been working fine before and after my 7m conversion.

Basically I found my temp guage in the dash wasn't connected to the water temp sensor in the thermostat housing, rather it seemed to be connected somewhere behind the dash. I wasn't aware of the two temp sensors for the climate system, I'm assuming that it was most likely one of these that was used for my temp guage previously(I've now got it wired to the correct temp sensor).

Going on from there, because whichever sensor it was wired to appeared to be giving me incorrect readings, are these possible to replace? I'm assuming that the one that detects coolant temp >50 has failed as I don't get any heat at all from my system.

[82MKII]

I also have cruise control installed and working - would I be right in thinking that it is vacuum run as well.

Gibbon,
sorry for the slight change in direction, but with my engine about to go in I was wondering if I would need to make some changes to the factory cruise control system, as it is vacum operated.
Have you found that you didn't need to do anything to it?

Thanks

Peter

[ViPeR_NiPPleX]

I've found the factory cruise doesn't like seeing boost... I believe the little canister near the washer bottle is a vacuum source. Or just a massive filter, not sure yet

[Gibbon]

Mine worked without any modifications - before and after the conversion.

The vacuum line from the actuator is plugged into the metal nipple just above the brake booster, which is on the metal piping that runs the length of the firewall.

Hmm, perhaps I need to connect the climate control off this connection if it's vacuum only