Hi,
I have an honda accord 1990 petrol whose AC system is stuck to cooling. Even if I move the know to maximum heat, it is still cooling. I have to point out that the AC button is stuck and so it is always pushed. Is that the issue? I want to understand what the issue might be before, maybe, buying a new "controller" (if that's how it is called that thing with all the buttons and *****).

 

On a related note, would you know how I could find a replacement for that control panel? I mean, how to find the exact part number... thanks.

 

If both the AC and heater are on, it will blow cool air.

If it is a problem of just the AC switch being stuck, pour some rubbing alcohol over the switch while pressing it and see if it is just stuck from grime over the years.
If that does not work, just pull the fuse (under dash) 2nd choice would be to full the relay under the hood in that fuse box. When that ac switch is on, it turns on the secondary radiator fan. This will make your engine run colder and make a poor heater in the winter. Just ensure that that fan is not on when you pull fuses.

As far as getting that part, I have no idea besides asking for one via people here on the website and possibly Ebay. It should just be the switch and not all of the ***** etc.

If the AC is not running, you can also look under the hood on the passenger side at the heater mechanical valve (on the heater hoses near firewall) and make sure that it is working when you move from hot to cold.

 

thanks, good to know. Indeed, the button was stuck because, as it can be seen if you look closely at the picture, there was a small wooden piece under the button. It was put there on purpose, since now that I have removed it the button does not retain its pressed status.
Anyway, even with the button not pressed, no hot hair. I think it should be the heater mechanical valve. What if it is stuck? Only the mechanic can help?

Thanks.

 

If the switch doesn't move, just disconnect the wire on that switch (under the hood) and move it one way for hot and the other way for cold when using the AC in the summer. Sure, it is not a make it work like it is new fix, but you get a hot heater and a cold AC. Then you can take time later to find out why the cable is not opening and closing the valve, or if it is a bad valve.

If this is not the issue, then you may be getting a plugged heater core.

 

Also, pay attention to your engine temperature. If it is not coming up to the normal operating temp, it could be a bad thermostat. (upper radiator hose to the cylinder head)