W107 Heater/Air conditioning

[Testie]

I think I have tried everything but am I missing something?
The "eye ball" vents when open blast hot air. The dash levers make no difference. So with the air conditioning on , all 4 levers down, fan on 3 ,you can get fresh air to the other vents but not refridgerated. The condenser and dryer have been replaced and new gas.The clutch is definitely coming on and the hot water tap is closed. I have fitten an extra termo. fan in front of the radiator to help cool the air conditioning radiator but that has not helped. I will have the gas pressure checked tomorrow but in the mean time is there another heater pipe that enters the cabin. If not how are the "eyeball vents" getting hot air? I only have one tap and one set of vaccum pipes, but it does appear to shut the water off. If open the dash levers it will cook you in seconds, great if it was snowing but it isn't at the moment.
Any help appreciated.
Col.

 

[Michel]

When you've had the car regassed, did the A/C person test it?
If so what was it reading at the vents?

 

[Testie]

Yes but I don't remember what they were. Not as low as a modern car I think.
Col.

 

[Michel]

Are you sure there is no leak?

I would get the A/C guy to come and check the gas first.

 

[Oversize]

I'm thinking it's got nothing to do with the sources of hot and cold air, but more to do with the vents. Perhaps one of the flaps has jammed, the lever's broken, the foam seals have perished and dislodged, or a vaccum leak / vac servo failure that's developed?

 

[Testie]

OK it is book in next week to have the air conditioning checked but if the vaccum operated tap on the firewall is "OFF" then how can there be hot air at the eyeball vents? (The replacement tap is plastic)
If the tap is not turning off completely and the hot air is mixing with the air conditioned air would that explain what is happening. ie. hot on the eyeball vents and outside temperature on the other vents?
Col.

 

[Oversize]

I still think it's a vent problem in (or on the outside of) the heater box. That would explain the difference in temperature and when that's corrected (and the temps the same) you may find that it's also cold. If not, then you have another problem (probably a refridgerant leak)...

 

[Testie]

So the air at the eyeball vents is the same air as the other vents?
Col.

 

[Styria]

So the air at the eyeball vents is the same air as the other vents?
Col.

Hi Testie, I would be very interested as to how you are getting on with solving your problem. Unfortunately, I am not much help in this instance as I have never had to deal with this problem on a 107. I did have a chat to someone very, or quite, knowledgeable with this work and he indicated that the job was worse than on a 116, and that's saying something.

He felt, like Mark, that it'd be a problem with flaps, and he ventured the opinion that really the whole heater box should be removed from the car altogether. Not nice, as it involves removal of dash, gearbox console, seats and perhaps even the removal of the front screen. I'll see if I can find more concrete information for you. Regards Styria

 

[Oversize]

Testie, check your Owners Manual for the operation of the vents. It should explain the HVAC system and what air you should get from what vents.... I'd certainly try everything else before pulling out the heater; it gives me a headache just thinking about doing it!

 

[Testie]

Work comitments have put things back a couple of weeks but I will continue until the problem is solved. I have read threads on removing the heater box and that will not be happening if it at all avoidable!! I still do not understand how I can have hot air blasting through the eyeball vents if the heater tap is turned off and no water is circulating. Am I still on the wrong track or is there another source of heat?
Col.

 

[Michel]

I still do not understand how I can have hot air blasting through the eyeball vents if the heater tap is turned off and no water is circulating. Am I still on the wrong track or is there another source of heat?
Col.

Ok.. let's try and think.

Have you had the car for long?
If, yes, then when and how did this problem start?

If you just got the car recently, or not that long, play with the levers the other way around... You might be surprised..

 

[Testie]

I have owned the car for a little over 12 months and I did not do the restoration but I did replace the A/C compressor and dryer reciever and blower fan last year. The car does not get out much but it appears that the problem has always been there to a certain degree. I am fairly sure the air con. was cold after the compressor was fitted but occasionally it blow hot air usually when slowing down for a town speed limit. This is why I fitted external fan to aid in cooling the air con. radiator. All four controls are down which should give maximum cooling?
I initally thought that the heater tap (new) was loosing vaccum and turning on when the engine slowed but that is probably not correct as there is more vaccum at idle isn't there?
I will keep you all posted as I find out more.
Thanks,
Col.

 

[Michel]

I would start the car and let it warm up.

Then change the levers positions one at a time and see if there is a difference.

 

[Testie]

Thanks I will try that tomorrow and see what happens.
Col

 

[Testie]

OK a day of travelling and trying different positions did little to help sort this problem out. With all levers down air cond. air to center three vents and it appears as if the two eyeball vents on the sides just give outside temperater air. So turn them to clsed and all is well untill a sudden blast of hot air to the demister vent which overpowers the air con. then for no reason it turns off and all is well again. The only thing I can link to the change is engine load so next trip I will wire the vaccum tap to closed and see what happens.
What temperature would you expect from new compressor, drier and auxillery fan on a mild day say 20*. Is 5 * at the vent good?
Where do the vents go that enter the doors?
Col.

 

[Michel]

OK a day of travelling and trying different positions did little to help sort this problem out. With all levers down air cond. air to center three vents and it appears as if the two eyeball vents on the sides just give outside temperater air. So turn them to clsed and all is well untill a sudden blast of hot air to the demister vent which overpowers the air con. then for no reason it turns off and all is well again. The only thing I can link to the change is engine load so next trip I will wire the vaccum tap to closed and see what happens.
What temperature would you expect from new compressor, drier and auxillery fan on a mild day say 20*. Is 5 * at the vent good?
Where do the vents go that enter the doors?
Col.

Definitely something not right there....
You should be getting around 5-8C at the coldest...

Let's see what the A/C man says..

 

[Michel]

Col,

Are you in or near Sydney?

 

[Styria]

Hi Testie, as we have had no update, I am not certain if this post is still of relevance. I did have the opportunity the other day to have a closer look at the heating/cooling system on a 450SLC. Whilst I cannot diagnose your problem, I can confirm that:

1. The dash top can be removed without removing the front screen. However, obviously one needs to remove both seats and the centre console.

2. There is not a lot of difference between the 116 and the 107 system. In fact, they are about identical with sliding levers controlling heat and cold, face level and/or feet distribution, and the heater box also has the bottom section of the heater box that requires removal to gain access to the flaps that control the flow of air.

3. In addition, of course, you have the two micro switches that are activated by downward movement of the levers.

Okay, you have indicated that you have been able to shut off the hot water tap situated under the bonnet on the firewall. Have you observed movement of the lever on that tap when activating the levers on the quadrant panel ?

I think it is important to establish that the tap is working at all times. Furthermore, the operation of the Air Conditioning dial is dependent upon there being gas in the system and with the fan turned on. That's about all I can raise at this time. If possible, try and get back to us. Regards Styria

 

[Testie]

Back again! Just had a week touring in Northern NSW with reasonably high ambient temperatures (30 * +). the car went like a charm BUT.......
First, before I went I had the air conditioning gas checked and all was OK
The air conditioning compressor is coming on as it should when the switches are in the correct position.
After a couple of hours I lifted the bonnet and put a zippy tie around the heater tap so it could never again turn on.
So the observations are.
1. The vents nearest the window are just outside fresh air.
2. The air conditionong on this car is not worth a pinch of poo.
3. The air is cooled but nowhere near enough to make any difference in the cabin. The termometer says the air is around 5-8* but with the fan on high it is still way too hot.
4. The roof was up most of the trip as the sun was burning us. This means there is little air flow through the car.
When time permits I will ring the compressor manufacturer and see if there is a different pully that might improve things.
Meanwhile more sunscreen and off with the roof for the summer.
Heading on holidays to mother England and a trip on the Rhine river in 2 weeks so not much will be done untill our return.
Thanks for all those who advised and look forward to any comments.
Col.