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Heat in 1997 accord not working

10K views 18 replies 5 participants last post by  Inspector1 
#1 ·
I have a 4 cylinder 4 door 1997 accord dx value package. Does anyone have a good picture or a good description of how to access the thermostat. My heat does not get very hot (it gets a little warm) but not warm enough to counter 15 degree weather so I am pretty certain I need to replace or fix my thermostat, but I cant figure out how to access it. Is it accessible from the top of the car or do I need to go under neath. Are there any other possibilities if my heat is not really hot?
I had this problem both before and after my radiator was replaced.
 
#2 ·
Welcome to DA.

Your problem may not be the thermostat, but rather a plugged heater core, especially given the year and if the coolanat hadn't been changed religiously over the years.

A co-worker had an older Integra suffering from the lack of heat for the cabin during winter time, he replaced the thermostat but it still didn't help, he eventually got rid of the car since other things were needing replacement from age/mileage.
 
#5 ·
IF your car has not had the engine thermostat replaced, then that's an immediate "Must Do." You can trace it from the BOTTOM radiator hose to (somewhere on) the cylinder head. Typically, it can be replaced in a few minutes. New thermostat, new "O" ring gasket, and 10MM socket on a ratchet for R&R, should do the trick.

May God Forbid that you need a heater core. It's an expensive, PITA job on most any Honda/Acura, as you typically have to remove the entire dash. :(
 
#4 ·
Heater core is like a mini-radiator, it sits around the glove box area under the passenger side dash, coolant comes into the heater core, circulates through it to release the heat needed to warm up the cabin.
 
#6 ·
The thermostat is in the housing that the LOWER hose goes to on you F22.
It will have a temperature switch for the fans in the housing and a group of ground wires that are there also.

If your temp gauge rises very slowly to the normal range, or never reaches its normal range in cold weather, the stat is very suspect. If it needs one, use a Honda stat, it should come with the gasket you need.

If the temp gauge goes up quickly to its normal range, either the core is blocked or the heater control valve isn't opening all the way. The gen 5s were really good for breaking the temperature control knob, it'll only turn it part way.
Pull the knob off, is it cracked?
 
#7 ·
The thermostat is in the housing that the LOWER hose goes to on your F22.

If your temp gauge rises very slowly to the normal range, or never reaches its normal range in cold weather, the stat is very suspect. If it needs one, use a Honda stat, it should come with the gasket you need.
Mistake noted, and correction so made. I meant to state the LOWER radiator hose. My mind is working backwards today. :(

(Fred, I was thinking my trusty '86. Bottom hose runs straight to long, metal pipe which feeds the water pump, at rear of block. Top hose is return side, from the thermostat housing to the top of the radiator.)

Thermostats in the older Gens tend to be problematic. A redesign around Gen Four/Five has helped matters. Be all that as it may, I strongly recommend replacing the thermostat every two (2) years, regardless. And use ONLY Honda Type II (Blue) coolant.
 
#9 ·
The temp goes up quickly. How do I declog the heater core or get to the heater control valve. Is there a place where it shows a clear diagram to access it?
My gut tells me you have a defective engine thermostat. I strongly suggest you START by replacing it. Speaking from the voice of painful experience, you'd be amazed how quickly a defective $10 part can wipe out the entire engine. :(

However, it is also quite possible you have a defective temperature sending unit. It should be located on or about the thermostat housing. It is also possible you have a malfunctioning temperature gauge. But again, I strongly recommend you start by replacing the engine thermostat. It is the central control over cooling system operation.

Swing by your dealer and look at the (Helm) factory service manual for your car. Else head to AutoZone, O'Reilly's, Advance, etc. and look it up in a Chilton's, Motors, or Haynes guide.

I seriously doubt you will be able to unclog the heater core. If it's defective, you'll have to replace it. Ditto for the heater control valve, which you should find somewhere near/on the firewall.
 
#10 ·
The heater control valves on 5G's get gummed up from the elements and stick which binds the cable and tends to crack the inside of the temp control knob(As Fred stated). You would remove the knob by pulling straight out and check the inner part that goes on the metal shaft from the switch inside the dash, if that is broken you would need to buy a new knob. The heater control valve is located in front of the passenger side firewall(engine compartment)
It is approx 3" long and is installed in the heater hose from the engine to the cabin compartment. It will have a cable attached to a lever on the knob. Get some WD40 to lube the parts but first try and manually move the lever back and forth(open & close)on the valve...lube as needed. If the valve is stuck (the reason that knob is broken also) in the cool position it will not allow hot water to flow into the heater core (in the dash/pass side) If the valve is not sticking then the htr core is the next item to address.

Unfortunatly I don't still own my 5G or I would post pictures:yes:

Here's a shot of a 6G valve(at least it gives you an idea what it looks like..:yes:

Hope this helps.

I1:)
 

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#11 ·
Yes, you are right, I have replaced several knobs. That is a sensible explanation, hopefully you are right. I have noticed even after replacing the knob that it does not seem to move in a very even fashion and can be kind of jerky. I will take a look tomorrow.
 
#13 ·
Before you try to replace the heater core try this:

Make 100% sure that the temperature knob on the dash is NOT broken. It is so common on those cars due to the fact that you're pulling the cable for the heater control valve. If there's any stiffness in the cable the knob breaks.

If that's ok move on to this:

Drain all the coolant from the car.
Gain access to the 2 heater hoses going to the heater core.
Have about two 3' sections of 5/8" heater hose available. Have 2 gallons of Type 2.

Remove the 2 hoses from the core.
Put each section onto the core's pipes.
Take a garden hose, and stick it into 1 of the hoses, place the other in a 5 gallon bucket. Run the hose at FULL pressure through the hoses and core.

Then remove the hose and put it on the other one, so you can reverse flush it.

If when doing this you can't get any flow through the core, you're screwed. If you do, great.

Now, if you had flow, take an air source and gently blow all the water out of the core.

Connect the hose without the valve on it.

Check the hose with the valve, that the valve actually opens all the way.

Once you've verified the valve is capable of opening all the way. Put that hose back on the core.

Now, open the bleeder above the thermostat housing and fill the system with the new Type 2 you bought until coolant flows from the bleeder and close it.

Complete filling the radiator and cleaned out reserve tank.

Put the cap on, start the car, run it at 2000 rpm for about a minute, carefully remove the cap, and top off as the core will have filled.

Put the cap on. Run the engine at 3000 rpm for at least 5 minutes. You should have very good heat (place system on face vents with full heat). A very good vent temp should be what I got out of a 2004 Civic coupe (195 at 3000, 170 at idle).

If you still don't have heat, it's time to find out whether your water pump is actually pumping.
 
#14 ·
cant find the cable

I opened the hood and this was the only mechanical cable I could find. The first picture shows the cable that is connecting to the dash and the second picture shows the thing it is moving when I manually pull the cable. I dont see this cable move when I turn the knob, though.
 

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#17 ·
Ah, Ok, now I see the cable from the dash you are talking about in the left side picture.

I'm not familiar enough with what the heater control valve looks like on these cars as in the right side picture, so you'll have to wait until Fred chimes in.

In the mean time, why not move the valve to the full open position to see if you now have good heat?
 
#18 ·
The heater control valve cable comes out down near the bottom of the firewall near the heater hoses going into the car.

I honestly can't tell what the second pic with the rectangle is showing. Possibly the transmission tv cable. Does it move when you rotate the throttle lever on the throttle body?

The heater valve cable should look nearly identical to the one in the gen 6 pic posted earlier.

The cable coming out of the firewall should be the accelerator cable or if you have cruise the cable that goes back to the accelerator pedal.
 
#19 ·
You need to look on the side w/arrow that has been added.... passenger side firewall...

I1:)
 

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