Any thoughts? I can barely even get warm air. A/C works just fine.

 

Sounds like the engine is running nice and cool. How are your water temps?

I am running a Koyo rad, and Mocal oil coolers and it takes a long time to get heat in the car. I am even running a stock temp thermostat. If you have an upgraded cooling system with even stock twin oil coolers it will take a while on those cold days to get up to temp.

 

Any known history of a "Stop Leak" type product being used in your car's cooling system?

 

Where are you checking the temp of the outlet air?

If it is the face vents then that is as warm as it gets as it is a safety feature. Make sure you are checking at the defroster or the foot vents.

 

Mine did the same thing it would barley blow hot air, when i switched from hot to cold it went up maybe a few degrees after an hour or more of driving. i bet that will change during the summer months but winter was cold.

 

As have been hinted at in the prior posts there are a handful of causes.

1. Car's coolant isn't reaching operating temperature - typically caused by stuck open or partially stuck open thermostat.

2. Heater core is clogged - typically caused by poor maintenance of the coolant system allowing rust or other particulate mater to clog up the heater core proper or the inlet/outlet. A stop leak type product could cause this.

3. Valve controlling amount of coolant flow into the heater core isn't opening fully - could be a faulty valve or a faulty hvac control switch in the cockpit.

 

Thanks for the input guys

This was on a fairly lengthy drive - about 3 hours (First nice day in a while!)

As far as I know there hasn't been any use of a stop leak type product - the car has always been well maintained (it was previously owned by sixrotors here on the forums)

Yes I'm talking about the temp of the air out of the face vents, (hand vents? lol) but I still would expect it to get warmer.

Water temp is dead middle on the stock gauge - but we all know how **** that gauge is. This is going to be a troubleshooting headache - luckily it will soon be warm enough out that I wont care lol

 

In my case, the air-mix door actuator has failed. It wont move the air-mix door to allow hot air into the ducting. Thus no heat ....... ever. I have been told that the entire dash has to come out to replace the faulty actuator. Because all of the plastic dash parts are so old and fragile, I have opted not to repair it. I would rather have a solid dash than heat.

 

The air will NOT ever be hot out of the face vents. It is a design feature of the system.

 

Switch the heat to feet only and see if that gets hot. If it does then you're fine.

If not, then your actuator is faulty like what adam c said^^. It'd require you to pull the dash if you want to fix it. I believe I saw a write-up a few months ago.

 

The FD does not have a heater core coolant flow control valve. This is most likely just normal operation. I can get some incredible heat in the cabin by leaving it on "feet" vents only.
A couple people in the past have noticed an improvement in heater performance after performing a very thorough heater core flush, but they actually had a problem in the first place.

 

This correlates with what I experience in my FD. My coolant is a little rusty though, so I could still have other problems. I hate it when people skip proper maintenance (new owner of this FD). I will try the foot/defroster next time.

 

try jacking up the front of the car and reving it a couple of time till it gets to temp level.make sure the heaters on full blast though. i did that on a rx8 it seemed to work but maybe the designs different?

 

Adam c is on the money. Very common in fds. That's my problem too. Just dress warm.

 

Thanks for the input guys - I think I noticed it was warmer on the foot vents, so I think it's operating normally. This was the coldest weather I've ever driven the car in, so I guess I just hadn't noticed before.

I have a proper DD too, so luckily I can live with it as is.

Thanks again folks.

 

Mine only works if I have it set to defrosts....works so well that I have to turn it down.

 

Now that it is mentioned, I do recall the defrost and floor heat was much better. I don't drive it in cold temps very often. This is something to keep in mind!

 

check your coolant level also, make sure its topped off

 

At around 166,000 miles I had to reverse flush the core to remove accumulated debris and restore decent performance. A lot of gunk came out. Additionally, I have noticed that the FD doesn't seem to have much differential pressure across the core, and, therefore, not a very high flow through it; which likely exasperates the problem.

 

I believe I have a similar issue. My feet vents and the defroster work GREAT. They get nice and warm. However, hot air NEVER leaves the dash vents...not ever. I'm not excited to hear that the duct flap requires a total dash removal....