So my 90 ef si heater doesnt work corectly.

So the 1,2,3,4 speed changing works

And the tempature change works, kinda, it goes from cold to kindda not cold. And my car fully heats up.

And the switch that controls where the air goes doesn't work. The switch moves but doesn't change where the air goes. It only comes out of the front vents. How do I fix it so that it is fixed or stuck on defrost atleast...

And why is it not blowing out hot air?

 

Wassup boss??? I read here on HT somewhere last week about this and I'm also having the same issue as far as the heat not being HOT... its like barely warm when it used to be blazing!!!
Someone mentioned that the little flapper valve need to be replaced thats in the engine bay right up on the firewall where the2 rubber lines go into the car for the heater core...
Not real sure if thats the answer to that fix but I was also wondering if anyone else has had this issue and correctly fixed it!!!

 

the no heat issue is addressed in the FAQ. and its probably NOT what the above poster said...

i dont know about the vent selector. probably a bad electrical connector. i know on the crx its electrically operated, the civic might be different.

 

I dont think its electricly operated since its not a push button changer. Its a lever that moves manualy and in my buddys ef I can hear it moving manualy.. Any other input? Ill check out the faq tho thanks... And I will also look into that valve... Any other input? Thanks guys

 

Sounds like my car was. My temperature dial was broken when I bought my car (3 years ago) so I have my heat manual opened in the fire wall as well as under the dash. I had heat for a while then last winter I tried it out and it was just cold air.

Finally being frustrated with a freezing cold car, I hooked up a garden hose to the inlet hose of the heater core and put the outlet of the heater core to a bucket and turned up the pressure on the garden hose. I could see the hose building up a lot of pressure and finally after about 30 seconds I herd a big burp sound and water came pouring out of the heater core outlet hose. I have had good heat since then.

 

So you think it is a plugged heater core???

 

Just explaining what happened with my car. I know that before I got my car the previous owner ran "bars Leak" through my system to try to fix the headgasket, and that clogged up some stuff.

I would check that all your vents and valves are open. Check out this thread on how to do so.

https://honda-tech.com/forums/honda-crx-ef-civic-1988-1991-3/heat-not-working-2225295/

 

Check the cables going to the flaps that change where the airflow goes to make sure that they are connected.
Look under the dash in the middle of the car on the heater assembly.
Let us know what you find.

As for the heater not getting very hot try a cooling system flush and see if that helps get better heat.

 

i have this same heater issue, when it stops raining im gonna see if my heater core is clogged up, but basically nothing is connected. my vent adjusters are cut my temp adjusters dials are cracked. how can i manually turn it to heat and manually adjust my vents ? im soooo tired of using paper towels and squeeges as my defroster... i have a 91 civic hatchback

 

im having an issue with my heater too except mine doesnt blow any air , i removed the blower motor and tested it and it does work , i changed the relay thats connected to it as well and nothing , also checked the 30 amp heater fuse and its fine , what can it be ???

 

Would this affect only the defroster setting? Cause I just bought a 90 Dx and the defroster doesn't work, but the heat elsewhere works just fine.

 

blower resistor

 

perhaps the cable that controls the defrost flap in the air box is unhooked or broken. orr the flap itself has an issue

 

does anybody know how manually adjust the flaps so that the air only blows for the windshield defroster ?

 

that black resistor with the plug bolted down to the side panel ? if it is i changes that too , unless theres more of those i dont see

 

How did you manually turn on the switch under the dash ? I know how to turn it on by the firewall but i cant seem to find the switch under the dash.