89 NA6 - no heat/AC - loose components?

[twr7cx]

The 89 NA6 that I recently purchased blows air through the air vents but doesn't seem to have any heat when the heat control is slid over nor does the air-conditioning seem to cool the air at all. This morning I removed the glove box in an attempt to look behind and try to diagnose the cause:



With my head down there I moved the outside air/recirculation lever and air position (i.e. windscreen, chest level, feet level, etc.) levers in order to identify and observe the operation of their linkages/cables moving the relevant parts - the movement seemed right.
When I moved the hot/cold air lever though I could not find anything else moving - is anyone able to advise where the linkage/flap/cable is?

The Denso plastic box with the clips securing the top half seems to be loose and not connected to the components either side of it:




You can see the gaps in the below photographs of each side where it should connect to the neighbouring component:





The back bottom mount also seems to have no nut securing it indicating that perhaps it was removed/played with previously?



This top bracket above it also goes to nowhere (I can't see anything nearby that it would go to):



I also found this bracket lying loose above it:



So, any tips/guidance on how to correctly reassemble this to try to get the heater/air conditioning properly functioning? Is there any obvious parts/components that are missing?

[KevGoat]

Here's a photo from my old NA6 that might help ...

[93_Clubman]

Might be something in following which provides clues:
1999 heater cable: https://www.miata.net/garage/heater_cable.html
Air Conditioning Installation (1999): https://www.miata.net/garage/AirInstall/index.html
NA6 was R-12 based AC, hence following conversion to & recharge of R-134a:
Air Conditioning - R-134 Conversion: https://www.miata.net/garage/r134.html
Air Conditioning - R-134 recharge: http://www.xanga.com/item.aspx?user=Jic ... =213551321

[twr7cx]

Thanks for that. I'll get to reading then!

By the way, anyone aware if NA6 and NA8 components are cross compatible for this? There's a local guy wrecking an NA8 so I can acquire things like the clamps etc. from him if they will be suitable for me NA6 too...


[QUOTE=Llama;8774279]I assume the AC lines that go through the firewall into that box are connected?[/QUOTE]

Yes, I believe that the connections to the heater core and evaporator are fine on the firewall side:

[93_Clubman]

anyone aware if NA6 and NA8 components are cross compatible for this?

NA6 AC was R12 whereas NA8 AC was R134a - there were different parts, plus variation locally as AC was fitted here. But as yours appears to be a JDM NA6, ie a Eunos Roadster, your AC if original will have been fitted in Japan, so case by case basis for parts compatibility.

[twr7cx]

[QUOTE=tomthedog;8776316]First the heat:

Just want to hit the obvious, you did check the coolant level & the car is hot - right?[/QUOTE]

Yep. Have checked the coolant level in both the expansion bottle and radiator. Both are full.



Could there be an air bubble in the heater core? Is there a way to bleed the cooling system?


[QUOTE=tomthedog;8776316]Unsure of the RHD but, the LHD cars have one adjustment cable on the drivers side foot-well (vent direction). The other two cables go behind the glove box (temp mixer & air source). If your vent direction is on the passenger side, then the temp mixer is on the driver's side.[/QUOTE]

Thank you. Not sure why but I didn't even think of checking on the steering wheel side. Put my head under the dash and there it was. Moved the lever and the cable and mechanisms moved smoothly in what seemed to be their full required travel. So I assume the issue is therefore not with this. Why I then don't have heat I don't know...!


[QUOTE=tomthedog;8776316]The AC:

Fuses good? Does the AC button light up? Is the fan speed on 1 or higher? For USDM cars this is needed.[/QUOTE]

I removed, checked and refitted every fuse that I could find on the vehicle (under the dash and in the engine bay).

I then went looking for the relay for the AC. I assume this is it?



Gave the connector a bit of a tap and jiggle.

Back into the cabin, started the motor, fan on 1, hit the AC button and bam the engine revs laboured and dropped down. Put my hands over the climate control panel and there was a blue light illuminated underneath the fan speed knob indicating that the AC was on.

I turned it off immediately after this out of concern that the evaporator is only loosely mounted (bottom mount nut missing as per pictures above and top mount nut loose) and missing the claps for plumbing to the neighbouring components. So hopefully the AC is now fixed. I will try to firm up the evaporators mounts and get some clamps and then test it properly.


The heater is now my main focus. Thanks heaps for the comments, thoughts and ideas so far!

[93_Clubman]

The 89 NA6 that I recently purchased blows air through the air vents but doesn't seem to have any heat when the heat control is slid over

Moved the lever and the cable and mechanisms moved smoothly in what seemed to be their full required travel. So I assume the issue is therefore not with this. Why I then don't have heat I don't know...! The heater is now my main focus.

As the heater core is always in the coolant loop regardless of hot/cold lever position on a properly working NA6, & as you appear to have full range of movement when hot/cold lever is moved, it would seem that coolant isn't getting to your heater core. What is apparent is one of the heater pipe clamps (the one furthest from the windscreen washer bottle) has been replaced, so someone has been working in that area.
It may be that the heater core was leaking & they've isolated it from the circuit, or when they've had reason to replace the heater pipe clamp, that they've damaged the thin walled copper piping that the heat pipe goes over. So it would be worth first confirming that coolant is able to get to the heater core.

[twr7cx]

it would seem that coolant isn't getting to your heater core. What is apparent is one of the heater pipe clamps (the one furthest from the windscreen washer bottle) has been replaced, so someone has been working in that area.
It may be that the heater core was leaking & they've isolated it from the circuit, or when they've had reason to replace the heater pipe clamp, that they've damaged the thin walled copper piping that the heat pipe goes over. So it would be worth first confirming that coolant is able to get to the heater core.

I removed the two heater hoses connected to the heater core.



Used the hose and blasted water through each way. Lots of much came out with the first blast and then every time I changed sides a bit more came out. Repeated this probably 30 times before the water was clear each way.

Reconnected, topped up the radiator. Took the car for a drive to operating temperature.



I now seem to have heat. It's not the greatest heater of any vehicle but it's warm air and that will be beneficial in our cold winters!

[93_Clubman]

will be beneficial in our cold winters!

Great result, especially living in Tassie in about 4 months time. Hopefully heat improves with a bit of time as it's now flowing & continues to flow. Keep an eye [& nose] out for leaks.

[twr7cx]

Hopefully heat improves with a bit of time as it's now flowing & continues to flow. Keep an eye [& nose] out for leaks.

Cheers. So far no water leaks in the cabin or engine bay.

Would the gaps/lack of sealing between the three components (blower, AC evaporator and heater core) effect it at all?

The cars got 187,000km + and I don’t have any service history so plan to do the timing belt soon which means I’ll change the water pump and flush through the entire cooling system then which might help to further improve the heaters performance...

[93_Clubman]

Would the gaps/lack of sealing between the three components (blower, AC evaporator and heater core) effect it at all?

My NA has no AC or PS, so can't visually inspect to make a definitive call, but if the gaps/lack of sealing between the three components had an influence then I'd expect the cabin to feel as if the heater were on, ie hot air would be escaping into the cabin.
Agree, given the state of the heater core, a baseline service is required.