1993 114 bhp mx5 heater problem

[carspath]

my 1993 mx5's heater used to blow out wonderfully hot air when requested to do so

now it only blows out luke warm air , just

the blower is fine , and works correctly at all the different fan speeds
I changed the radiator, and the radiator cap about 5 years ago , and they look fine , and the coolant level is fine

its just that the temperature of the air being blown out of the vents is now no longer as hot as I would like it to be

please could you tell me the likely causes, and their solutions

thank-you

[MX-5 Lazza]

Sounds like the thermostat is stuck open.

[carspath]

thanks mx5 lazza

is there anything I can do about it?-----?does putting the thermostat in boiling water help?
or do I need to get a new one?

[Oldandslow]

Not really repairable. Putting it in boiling water is the way to test that it opens properly but it sounds like yours is stuck open. Look at it cold, if it's not closed buy a new one, it'll be a fiver.

[Richiie]

Hi, iv heard that if there has been tap water in radiator then it can cause scale and rust to build up within the radiator and the hoses. If you look at the colour of the water in the rad then it should be green. If its another colour or if there is a residue (red/brown) at the bottom of the expansion tank (and maybe check some of the hoses) then you can need to flush the system with some cleaning solution.

[MonkeyDust]

Is the temp gauge reaching normal, usually just just below half? If it is, the next thing to check is that the temp slider on the heater controls is still connected to the flap, or if it is just miles out of adjustment, you may find this thread helpful www.mx5nutz.com/forum/index.php?showtopic=136773&a...