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Poor heat distribution in my 98 Acura 3.CL

Hey ya’ll I just bought a used 98 Acura 3.0CL. I’ve noticed that when the heat is cranked, it doesn’t blow hot at all. I did some quick research and came up with two answers thus far; check the antifreeze coolant and that I may need to replace the heater control valve. Am I “warm” on the area? lol Cheers!

Those are two possibilities, but let’s not forget about the probability that the cooling system’s thermostat is stuck in the “open” position.

I would suggest that you first check the level of the coolant, and that is the simplest task.
Don’t just look in the overflow container.
When the engine is totally cooled-down, open the radiator cap to check the level. If it is below the area just underneath the cap, then it needs to be replenished with the correct-spec coolant/antifreeze.

However, unless you know (from maintenance records) that the cooling system was flushed and the coolant was replaced w/in the past 3 years, then you should just go ahead with a flush/total refill with new coolant/antifreeze.

What’s your temperature gauge getting up to? Half way?

If the coolant level is ok, it’s more likely this symptom would be caused by a faulty engine coolant thermostat rather than a temp control valve. insightful’s comment above is spot on. If the coolant temp gauge on the dash isn’t getting to the 1/2 way mark or maybe a little higher once the engine is heated up (5 minutes of driving), suspect the thermostat. Thermostats take a lot of abuse and if this one is original to your car, that would be even more indicative of the problem being the thermostat. It’s old, the metal has corroded, the seals have deformed, and it just plain needs to be replaced. Not a big deal to replace a thermostat on most cars. Depending on how it is configured, it could be a considerably bigger deal to replace the heater control valve.

Thanks guys. Coolant levels are good, and it was flushed just last year. And ya’ll are right, the gauge only goes 1/4 way, doesn’t come close to half… looks like I figured out the problem.

Not sure if any of you would have a recommended brand here, but this is my go-to shop for parts… suggestion?,%20Housing%20&%20Radiator%20Cap&mode=PA

Running cold will also give you poor mileage.

I’d tend to go with the Stant OE Exact replacement.

I’d also be interested to know if you find the old one “stuck” open. When my Camry did this, the old T-stat was closed when I removed it but heating it in a pot of water showed it opened at ~150 deg. I concluded that the wax pellet that expands to open it had degraded to something with a lower coefficient of expansion. In any event, the new T-stat fixed it right up.

When I was searching thru Google for an OEM part, I came across this web forum for a 97, that seems to have the same issue. The majority of folks suggested that the thermostat was fine… I mean, this seems like a cheap fix to not try it out, but it’s interesting so many people say it’s not this.

Simple, these people are all wrong. Change the T-stat and report back.

I agree with insightful. If your temperature gauge is only going up 1/4 of the way it has to be the thermostat. That’s some crazy advice in that article.

I just read OP’s article

it’s amazing that out of all the people talking on that forum, only one correctly told the guy that he needs a thermostat

It’s also amazing that one of the other guys went to the trouble of putting his thermostat into a pot of heated water, watched it open up . . . apparently without any mention of the temperature . . . and put it back

If I’m going to the trouble of removing a thermostat, I’ll be putting in a new one, no matter what

@db4690, I wholeheartedly agree. Thermostats are cheap and changing them is cheap insurance.

Gotta agree. I couldn’t believe the advice on that web site. Even when its below zero, it doesn’t take long for an engine to overheat or reach operating temps. Removing the thermostat is not done anymore, and running an engine cooler may mean that it never hits closed loop operation. Must be kids.

So, I’ve been told that the thermostat was already replaced at an Acura dealership a few years ago when the problem started… and evidently didn’t solve the problem. I’m now wondering if it’s the valve…

If the temperature is still going up only 1/4 of the way then whole system is running too cold. Even though they claim to have changed the thermostat I’d change it again.

Is there by chance a summer vs winter thermostat (by summer meaning prevents car from overheating)? My dad (who isn’t a mechanic) seems convinced that the wring replacement thermostat was installed which didn’t fix this issue previously. Turns out it wasn’t a dealership who replaced the thermostat…



There is no separate winter and summer thermostat for your car

That said, it is quite possible somebody installed a thermostat with the incorrect temperature rating

That is one reason to get that part at the dealer. They will only have the part with the correct temperature rating. Whereas the parts stores will almost certainly also have thermostats with the incorrect rating. If the kid behind the counter doesn’t know his stuff, he’ll probably sell you the wrong one.

But at the dealer, that’s not an issue. Because the only choice is the correct part

There are two thermostat temperatures listed for that car - a 170 which is factory recommended and a 180. Either should give you heat. You previously stated that your temperature gauge is going only 1/4 way up. That’s the problem. Your thermostat is defective even though you stated it was recently changed. I’ve seen new thermostats that were defective right out of the box.

Where are you getting this information?

In my experience, the car manufacturer will only have 1 thermostat listed. And there will be no choices as to what is the correct temperature range

The problem is that the aftermarket gives you incorrect choices, along with the correct one