Mondial heater not staying hot please advise

Any leaks that you can tell? Puddles? Loosing coolant?

 

Okay, so it should not be the heater core (good news).

I don't have the shop manual for that one, is the heater control valve mechanically actuated?

 

Actually, I believe that the heater valve is electrically controlled. According to the older manual (for my '84), the valve is open when it is not activated, and closes when it is. So if it's closing, it is getting power from the rheostat control unit. Sounds like the sending unit is giving confused signals. Should be able to check that at the valve with a multi-meter. On the '84, the valve is located at the fire wall under the dash, IIRC.

 

This makes me glad that my old 308 just has a mechanical lever.

I hope it is not too expensive to repair. Don't buy anything until you call T.Rutlands and see if they have whatever part you need USED. It can save you lots $$

 

If you have access to a workshop manual, check to see if there are any troubleshooting ideas for the heating system. The 3.2 Mondials have an electric water pump/heater valve made by Bosch. Possibly this has failed or is corroded/crusty with minerals. Some MBZ and BMW models use the same or similar pump and there are kits available for some of them. I can do some more research if you determine this may be the culprit.
Brian

 

I have same problem with 89 mondial 3.2.
Havent investigated yet, but I hear the water coming thru then it goes quiet and the heat goes away. I am wondering if there is air in the system, there is a bleed valve on the top of the radiator.

 

I have the exact same problem, once the engine is warmed up you leave the control at max heat but with the stop PB in then you press the A/E PB and you get a brief burst of hot air then it goes cold again. therefore the heater is working and there isn't air in the system does anyone have the relavant pages in the manual they could send me a copy thanks

also have the old control box PB panel which looks like it has vacuum connections as well as electrical conectors may be tempted to open it up.

Cold but with still a silly smile on face whenever I drive it.

Jim

 

The Mondial hot water flow is governed by an electrovalve. If you look on page 47 of the 3.2 owners manual it is item #10. The air temperature sensor can be seen back on page 23 (interior fold-out) sitting under the driver's left side as item #49. Ensure that this little air channel (which has it's own little fan) is clear to recieve fresh current ambient air. See, once this thing warms up, it thinks the whole car is warm. Based on you initially getting the burst of warm air, I'd start with this sensor doofer or the rheostat as second possibility.
Would clean all air passages and wire connections. Remember, it even says in the manual that the system works gradually.

I agree with the honorable gentleman from Alabama - levers and cables are far more reliable.

best
rt

 

Living in Arizonia do you even need a heater?

 

The parts manual available through FChat sponsor Ferrari UK shows the parts. I've copied below so you know what the parts look like.
The electovalve ( circled as part #38) is called a 'heater valve' and is part #61079000 HEATER VALVE and is located on the starboard side of the car under the dash - you may even hear it click from time to time.
The sensor is shown with it's little fan (part # #61983500) which pulls the air over it. The sensor (#61079100) is about $100.
Image Unavailable, Please Login
Image Unavailable, Please Login

 

The system is fairly easy to diagnose. You can disconnect the eletrical connector at the heater valve. It's located in the car, in the upper right side of the passenger footwell.

I then plug a 12v noid light into the connector, but any small 12v bulb could be used. Turn on the ignition (you don't have to start the car), turn on the heater and observe the bulb illumination.

When the temperature reostat is set to full cold the light should be on continuously, with it set to full hot it should be off. In between those settings the light should flash on and off. The period of the flash is dependant on the setting of the reostat, the in-car temperature sensor and the heater temperature sensor. You will most likely find that the electrical portion of the system in functioning properly.

The typical failure of the system is that the rubber diaphragm inside the heater valve tears/disintegrates. You can check the valve by unplugging the eletrical connector (no power causes the valve to open), and running the car. The output from the heater vents should be hot. If it's not then the heater valve is defective.

The valve can be repaired. BMW and Mercedes use the same basic Bosch valve, and valve insert repair kits are available from them for much less than a new valve. It is also available from Bosch through aftermarket suppliers.

To replace the insert, first drain the cooling system, then unbolt the valve from the footwell, but leave the hoses connected. Then unscrew the four screws holding the insert into the body. Remove the insert along with the coil. Replace the insert, being careful to make sure that the wiring to the coil is aligned with the notch in the coil, so that it doesn't short out.

Before you refill the cooling system, plug the electrical connector back in, and check that the valve functions. You should be able to hear the valve click/thump as it opens and closes.

Good luck!
Brian Brown
Patrick Ottis Co.
Berkeley, CA

 

I took a look at the heater control valve and found that its getting permanent 12v with no pulsing on and off whatever the temp rheostat is set to, so when I pulled the plug off I I had a hot car, had a look at the temperature sensor on the drivers side and put a meter across it it seems to work the resistance goes down when its heated and resistance rises again when cooled. My next step is to open up the center console and test the rheostat. where does the control box that compares the required temperature and the current temperature and produces a pulse to control the heater valve live?

Thanks for the advice in the previous posts.

Jim

 

One other thing to check is that relay "m" (a Bosch ...101 relay mounted on the AC unit itself) is not stuck (or dead) and is getting the right signals. The way the water valve system should work is (TR have the same approach):

1. When the key is "on", the BR wire to the water valve 63 is always at +12V and the MN wire going to terminal 85 of relay m is also always at +12V.

2. When the AC "STOP" button is pushed, the GV wire going to terminal 86 of relay m is left open (i.e. not connected to anything) -- so relay m is not actuated and the ground signal on terminal 30 of relay m is connected to terminal 87a which in turn applies a ground signal to the MB wire going to the water valve. Since +12V is now always present across the water valve, it is held always closed.

3. When any of the "active" AC buttons is pressed, the GV wire at the pushbutton unit is connected to ground, which puts terminal 86 of relay m to ground, which actuates relay m and breaks the 30-to-87a connection. This removes the constant ground signal from the MB wire side of the water valve and that MB wire is now controlled by the AC ECU.

Just some things you might check (if you can find relay m )

Alternatively, if you just remove relay m from its socket and turn the heat "on" and still measure +12V across the water valve (i.e., no heat) -- this would be a bad sign for the ECU.
Image Unavailable, Please Login

 

This does not sound right at all. Are you sure that you have adequate coolant in the system and it is properly bled? Draining, flushing and refilling would be a lot easier than chasing down anything electrical in a Mondial and even if that doesn't solve the problem, you are no worse off.

 

Jim,
The heater control unit is under the passenger footplate. It is a plastic box with two 6 pin electrical connector. There are three temperature sensors in the system: the in-car sensor in the dash, the heater core sensor that plugs into the front of the heater core, and the evaporator sensor that is in the left rear of the evaporator. Since you are only having a prolem with the heater valve, then only the in-car sensor and the heater sensor come into play.
The easiest way to check the resistance of the sensors is at the connector for the control unit. The service manual has a very good description of which pins to measure across and what the resistances should be.
The heater and in-car sensors should be 32k ohms at 0 degC and 5k ohms at 40 deg C. The temperature control potentiometer varies from 0-10K ohms.

Brian

 

There is a little fan that is supposed to pull air through it (see picture previous post below):
I'll bet if you take the fan out, clean out the crap and clean the connections it will work just like new (whatever that was... )

 

How does one get at this little fan without breaking anything? Does the temp sesor in the dash just pry out? Do I have to tear off the glued carpet on the side footwell oanel, remove the panel to get at this fan? Is there some obvious way to tell if the fan is going on and working? Can you hear it, when does it go on, how long does it stay on? I would appreciate any practical help here...

 

Push the button harder.