No heat or AC

I have a 94 accord that I bought a couple months ago. This winter was no fun because I had no heat, I think it is a clogged heater core. I dont have that much money so I didnt bother fixing it. Now that summer is coming I would like some AC. Today was in the 60s here in Connecticut so I tried out my AC with no luck. After 10 minutes I knew no cold air was coming.

So I have questions on what I should do and what to look for. My first thought is freon. Do I need it to be recharged? Where can I find this? Is it the compressor? Where should I look to fix my problem? Could this be related to my no heat problem? What do you guys think?


Thanks I really need some help on this one.

first off i would try to recharge the system with freon. you will have to take it to someone who is lisenced to recharge the system because it is r12.

Look at the A/C compressor when you have it on, see if the clutch on it is engaged, or just stationary. If it is turning, your freon level is fine.

Are you getting adequate airflow from your vents? Some older car's heat/A/C cores get so slimed up with mold and dirt, no air can blow through.

Otherwise I'd suspect a problem with your dashboard control or the blend door assembly.

See if your heater hoses are hot into and out of the core, where they go into the firewall. If one is real hot and the other is cool or lukewarm, the core is blocked or the heater control valve is stuck.

Look at the A/C compressor when you have it on, see if the clutch on it is engaged, or just stationary. If it is turning, your freon level is fine.

Are you getting adequate airflow from your vents? Some older car's heat/A/C cores get so slimed up with mold and dirt, no air can blow through.

Otherwise I'd suspect a problem with your dashboard control or the blend door assembly.

See if your heater hoses are hot into and out of the core, where they go into the firewall. If one is real hot and the other is cool or lukewarm, the core is blocked or the heater control valve is stuck.

I checked my valve before and it moved back and forth. Ill have to try and reach to see if I can feel the pipes. I think the core might be blocked because the air doesnt seem to be coming out that fast, or as fast at it should. Would this cause no heat and ac?

Hmmm not fast. So you basically have one speed on the blower?

The knobs arent broken and just not turning the switches right?

Hmmm not fast. So you basically have one speed on the blower?

The knobs arent broken and just not turning the switches right?

Good point.

Think of it this way. You have to have a few things for it to work right.

Heat/Cold at the core(s)
Proper mixer/blend operation
Good airflow through cores and ducts
Working blower and blower speed control
Working dash control

You can verify core temps and and A/C compressor operation under the hood. If the compressor engages, the low pressure lines get cold and sweat, the high pressure lines get hot, your A/C is fine. If you have hot flow in and out of the heater core while in a heat setting, your core and heat control valve are good..

If you can hear the plenum door change position when you go from heat to cool, and the flow is redirected to the proper vents when you select DEF-FLOOR-VENT, etc, then the control and the blend system are OK.

If you have a blower that changes speed with settings, and strrong flow from the vents, your blower and ductwork are OK

When the cores get blocked, the blower usually sounds louder than normal, as it is blowing into a restriction, and little or no flow comes from the vents. What you do get should be warm or cool according to how you are set, just not enough flow to change the interior's temp.

If you just seem to get the same temp air no matter where you are set, then there is a problem with the blend system that meters where the blowers air is directed at the cores. These problems usually trace back to broken or popped off vacuum lines, broken cables, bad actuator motors, broken dash temp control switch, I don't know exactly what the system looks like in yours.

Make sure your outside air intake isn't blocked as well (usually up on the cowl, below the windshield) If you get a lot of leaves and stuff covering the vents, you loose airflow too.

Good point.

Think of it this way. You have to have a few things for it to work right.

Heat/Cold at the core(s)
Proper mixer/blend operation
Good airflow through cores and ducts
Working blower and blower speed control
Working dash control

You can verify core temps and and A/C compressor operation under the hood. If the compressor engages, the low pressure lines get cold and sweat, the high pressure lines get hot, your A/C is fine. If you have hot flow in and out of the heater core while in a heat setting, your core and heat control valve are good..

If you can hear the plenum door change position when you go from heat to cool, and the flow is redirected to the proper vents when you select DEF-FLOOR-VENT, etc, then the control and the blend system are OK.

If you have a blower that changes speed with settings, and strrong flow from the vents, your blower and ductwork are OK

When the cores get blocked, the blower usually sounds louder than normal, as it is blowing into a restriction, and little or no flow comes from the vents. What you do get should be warm or cool according to how you are set, just not enough flow to change the interior's temp.

If you just seem to get the same temp air no matter where you are set, then there is a problem with the blend system that meters where the blowers air is directed at the cores. These problems usually trace back to broken or popped off vacuum lines, broken cables, bad actuator motors, broken dash temp control switch, I don't know exactly what the system looks like in yours.

Make sure your outside air intake isn't blocked as well (usually up on the cowl, below the windshield) If you get a lot of leaves and stuff covering the vents, you loose airflow too.


Thanks for such a detailed explanation, it is really helping me. I know my fan speed settings work, although I think they are a little restriced which is probably related to the cores. I can change where the air comes out of so that is also good. I also know my dash works because when I turn from hold to hot I saw the vavle move in my engine. The problem must be my cores are blocked. I also have to check my ac compressor to see if that works, I think it does.

My question is how to unclog the cores. I thought the heater core was inside the firewall behind the center console. Since it was hard to get to I never looked at it. Where is the ac core and how do I unclog it? If I take it to my local shop, how much will they charge to fix my problem? Any tips?

Thanks a lot guys, your really helping me out.

If the core is clogged then by putting it to A/C the amount of air coming out should increase because you bypass the core altogether

If airflow through the cores is bad, you will just have to dig into it to gain access. I don't have specific info on Honda, but someone here does, I'm sure. Sometimes the heater control valve can be broken inside, where the actual part that closes off the coolant flow to the core isn't attached to the shaft that turns to close it, so moving the shaft doesn't do anything. Ususally if this happens, it stays open, and you can't stop the heat.

By gaining access to the cores, you should be able to see the problem, whether it is bad airflow through there, or a problem with the doors that direct airflow through them. There are products made for cleaning mold and crud out of them if they are blocked. Something like Lysol liquid cleaner and a soft brush will work too.

I had a similar problem at the house last summer. The core drain for my A/C got blocked, and so much water built up in there that mold took over the core. I couldn't get any airflow through the house 'till I cleaned it out. On my car ('97 Lumina) the cores are stacked so the air has to blow through both. When the A/C is on, the coolant flow to the heater core is cut, so you get cool air from the A/C core and vice versa. But when the A/C core slimes up, you get no airflow from heat or A/C. Yours could be similar.

This weekend Id like to look at my heater cores and solve this problem or Im going to send it to my local shop and waste some of my money :(. I have three questions.

Which is the ac compressor on my 94 Accord? Is it on top or on the bottom of my engine. I am confused on which pump it could be, and sadly I dont know which is which. How can I tell if its working? Which pipes should be cold or hot?

How do I know if I need some more freeon or coolant?

Lastly, how can I get to my cores. Im pretty sure they are inside the cabin and will be a pain to get to. Can someone please give me a link to a site that has great instructions or diagrams on how to get acess to them?


Thanks a lot guys.