I ran a search but I can't quite narrow down the problem to see whether I just need to replace my T-stat, or my heater core or valve is clogged, or if I need to bleed my coolant. Car is an 'S5 vert BTW.

A month or two ago, my coolant buzzer went off for no reason. I pulled aside, everything seemed fine. Temp gauge looked fine. Kept an eye on coolant throughout the week and wasn't losing any. Since that happened, every time I drive the car, the more often the buzzing came on. It would go away once my car was up to temperature or if I was on the highway (higher revs also make the buzzer go temporarily away.) But lately, its started doing it in city as well even when temps were fine.

Just recently, when I was driving and it was chilly, (car already warmed up), I turned on the heater but got nothing but cold air. My temp gauge began to rise. I almost pulled over but finally the heat kicked in and my temps went back to normal.

Now it seems that I don't get any hot air from the heater now and the temps start to climb steadily when I try and turn on the heater.

Like I said, I need to pinpoint the exact problem. I don't want to mess around trying something else when it might not fix it since I'm pretty busy.

 

Air in the system possibly. Try to bleed it.

 

You have air in the system. Bleed it.

Also, keep in mind that in order for the air to be in the system, you had to loose some coolant. You have a leak and are loosing coolant (most likely) or you have bad coolant seals. Find your problem before you cook your engine.

Autozone rents cooling system pressure testers that will help you find the leak.

Good Luck!

 

Thanks for the info guys. I'll have the coolant changed anyways since its due in. I just want to confirm if when I change the coolant and bleed it, was it the root problem of my heater not putting out any hot air?

 

Finding the leak first would be a better ideal since you don't want to waste good coolent. Bleed the car with the front pointing uphill helps bleed the air out of the system. Also bleed the cooling sys with the heater on full blast.

 

your heater will not give you alot of heat If you have Air in your cooling system..a pressure test will tell you alot.If the sytem loses pressure it will show up in the test.and if it is doing Just that then,two things right off the Bat could be an External leak like a Pinhole leak on One of the hoses or coolant seal starting to go...Best of luck though.

 

Dan, sounds to me like your watepump has failed.

 

If the water pump failed, wouldn't it almost always overheat??

Update: Changed the coolant over the weekend. However, the buzzer still comes on but not nearly as often as before. I got heat from the heater for a while but after driving it more often, it seems sometimes I don't get heat at all from the heater.

I'm still looking up old threads and I'm going to try a few more things this coming weekend but its kind of frustrating not knowing exactly what is the problem. I honestly hope the heater core isn't clogged. Such a PITA to change out.

 

Hmm...I'm going to check my air mix motor about the heater problem but I suspect something is still up with my coolant system and the annoying buzzer. But then again, the air mix motor shouldn't cause the slight rise in temps when I turn on the heater (even though no heat is coming out)??

 

If your car is overheating but not on the highway, it could be your clutch fan. Mine failed, and it would overheat when I wasn't moving fast enough, but you couldn't tell the fan was bitched. I forget how to check them, according to mazda I think you need a stupid RPM indicator on the fan or something stupid. Somebody else have a decent way to check it?

Anyways, if your car is overheating, you WILL lose heat at that moment cause the coolant starts to boil and air gets into your heater core. Every time I did cooling system work on a car when I was working in a garage, I'd have the heat on while road-testing it the first time because stock temp gauges are slow, if I'd ever lose heat, I knew the bitch was over-heating, often before the temp gauge started getting too high.

 

The fan clutch is working properly. In fact, since I've owned it, the car has never been overheating or overheated.

The only time the temps started rising only slightly (a lil more than halfway) was that one time I was on the freeway and I was chilly so I turned on the heater. As soon as I turned on the heater, I got nothing but cold air blowing at me. A little while later, the temp gauge only started to rise ever so slightly Thats when I shut off the heater and the temps dropped back to normal. I kept playing around with the heater controls until the heater finally started blowing hot air. Temps were all normal too.