Heater Blowing But Not Hot NA8c

smy0003 · Postby **smy0003** » Sun Jun 29, 2014 10:46 pm

Can you provide anymore info?
eg.
How 'not hot' is not hot? Same as the coolest setting or slightly warmer?
When did this start?
Have you been tinkering with anything relevant to this? Or anything at all?
Anything else playing up?

A short intro wouldn't go astray either; welcome to the forum

Nevyn72 · Postby **Nevyn72** » Sun Jun 29, 2014 11:14 pm

How long have you owned this car?

Check the hoses running to the heater core through the firewall.... Most common fix for a leaking heater core was to simply by-pass the coolant supply! :wink:

KevGoat · Postby **KevGoat** » Sun Jun 29, 2014 11:20 pm

Cable from the temp lever broken or dislodged?

Sent from my GT-P1000T using Tapatalk 2

KevGoat · Postby **KevGoat** » Sun Jun 29, 2014 11:59 pm

Try this for starters: http://www.miata.net/garage/heater_cable.html

This will explain where the cable is that adjusts the heat/cold. The article is for warm air creeping when vent should be closed but this will explain how to find and check if that cable is broken or not attached and maybe not allowing hot air in.

KevGoat · Postby **KevGoat** » Mon Jun 30, 2014 12:08 am

Do Nev's check first though as that's easy to see if the hoses have been removed or altered.

KevGoat · Postby **KevGoat** » Mon Jun 30, 2014 12:15 am

Btw ... one of the most useful sites to get to know "how to": http://www.miata.net/garage/

smy0003 · Postby **smy0003** » Mon Jun 30, 2014 9:53 am

KevGoat wrote:Cable from the temp lever broken or dislodged?

Sent from my GT-P1000T using Tapatalk 2

Was thinking this.

Nice car btw, don't see too many silver NA's around, and the wheels are nice too ;)

EDIT: Do you know what wheels they are?

KevGoat · Postby **KevGoat** » Mon Jun 30, 2014 11:35 am

Not the best image to show details, but the only one of my NA's engine bay that I could find on my computer of the area. Just shows where the heater inlet/outlet pipes run through the firewall. These pipes can often leak, so while there, may as well check them out and look around the area for any coolant.

Snowmotion · Postby **Snowmotion** » Mon Jun 30, 2014 4:10 pm

I don't think the problem is the kink! That is a loop between the inlet and outlet so there is no water in there from the engine to give you heat.

You will need to get it reconnected to the the system. (and hope there was not a reason for it to be disconnected)

Good luck.

aka_juffa · Postby **aka_juffa** » Mon Jun 30, 2014 4:19 pm

Dupain wrote:Checking the hoses ... seems there was some servicing and the hose may not have been put back on properly and a chink has developed. Getting an exhaust fitted this afternoon and will see if the mechanic can straighten it. Otherwise may have to purchase a new hose. Also what kind of coolant is required etc and where to fill up. Picture below.

Three words of caution;
1. In the engine bay the two heater hoses connect to soft copper pipes. Be careful removing/twisting the hoses as the copper pipes can be damaged.

2. If the original hose clamps are still in place it is recommended to replace them as they do not always work correctly again after being refitted. If you use worm drive clamps don't over tighten as it can crush the pipes, and you need to allow for expansion/contraction as the coolant flows through them.

3. One of the hoses has a interesting shape to it. Be sure that you don't try and un-kink the wrong one.

As for the coolant, just make sure you get the same color as you have now. Don't mix the 'green' and 'red' types. If you are unsure as to when the coolant was last replaced I would recommend a complete drain, flush and refill.

Oh, and welcome to the fun that is owning an MX-5.....and I do mean that in the nicest possible way.

J.

Snowmotion · Postby **Snowmotion** » Mon Jun 30, 2014 7:05 pm

It is hard to explain but i will try. I may be easier to meet some one and have a look at the stock set up.

The water pump sends water towards the firewall in a copper pipe on the bottom edge of the headers and it turns towards the passenger side at the end of the headers. (looking at that last picture that could be the bypass pipe the previous owner put on the car. If that hose is coming from a copper pipe below the headers then that is the one top follow)
The one closer to the driver runs to the back of the head.

Have a look on the net and I sure you will see lots of write ups about this. (perhaps use reverse logic. Look for video's on how to remove the heater pipes and work backwards)
Try this one. http://www.youtube.com/watch?v=d_ZAqUWRwho

aka_juffa · Postby **aka_juffa** » Mon Jun 30, 2014 9:12 pm

Dupain wrote:

Could there be a reason why they did not hook it up properly and not bypassing the heater with coolant?

That diagram provides a good view of the coolant flow. The only valid reason I am aware of for bypassing the heater core is if the core is leaking. The only way to fix it is to replace the core, which I. Have heard is a real PIA.

J

aka_juffa · Postby **aka_juffa** » Tue Jul 01, 2014 2:25 pm

Good on you for giving it a go.

While I have replaced the heater hoses a couple of times I have not replaced the heater core. Here is a link to a thread on the big forum by someone who has replaced the heater.

http://forum.miata.net/vb/showthread.php?t=367582

Good luck.

J.

KevGoat · Postby **KevGoat** » Tue Jul 01, 2014 5:50 pm

I remember it was awkward to get the clamps off behind the engine. Not much room to maneuver tools. Easy to get them back on though. Check for oil leaks while there.