| Author | Message | ||
     Richard Greene Frequent User Username: benzjag Post Number: 242 Registered: 12-2012 |
I discovered this morning I had no heat in my 79 Shadow. It was chilly here at 40F. The servo is "dead" and not working at all when I dial in heat with the upper and lower thumbwheels. The fans are blowing great. I switched the side boards from one side to the other on the servo with no joy! Is there a fuse for the servo? Any help greatly appreciated! I have never had this issue in 20+ years of driving Shadows! Richard | ||
| Alan Dibley Frequent User Username: alsdibley Post Number: 335 Registered: 10-2009 |
Hi Richard. The servo motors have a habit of sticking in one position because they depend on a wiping contact to operate properly. The contact gets a bit iffy and the motor does not turn. Bingo. But there are two motors involved - one for "Upper", one for "Lower". It could be that one of them has not worked for some time - it might not be obvious - and now the other has failed. If it is a fuse it is number 11 but that feeds other things too. When you turn a temperature control you should hear a little whirring noise from the servo. Remember that the knob must be pulled out to get heat, too. So a whirring noise for this action too. Alan D. | ||
| Robert J. Sprauer Frequent User Username: wraithman Post Number: 706 Registered: 11-2017 |
The car is 1979, does not have the pull out and rotate heat controls. It has two thumbwheels. | ||
| Jeff Young Frequent User Username: jeyjey Post Number: 455 Registered: 10-2010 |
There are still servo motors on the water valve and on the air control flaps. The linkages connecting the servo motors to the valves and/or flaps can also break, bend, or fall off. The electronics in the servo control unit can also fail, but if you switched boards without effect it's less likely to be that. My guess is the wiring to, or the servo motor on, or the water valve itself. | ||
| Jeff Young Frequent User Username: jeyjey Post Number: 456 Registered: 10-2010 |
(FWIW, I've had all of the above bar the water valve itself fail at one time or another.) | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 3244 Registered: 06-2009 |
I realize that the original poster believes this is a servo motor problem. But since this is a "heat thread" . . . I already mentioned elsewhere that the heater tap valves can fail, but since this is an SY2 car that's way less likely given the redesign in same for those cars. But you can also have the setscrew that holds the cable in place come loose, and not have the valve being opened and closed. You can also have times where, if the valve has been sticky, the cable itself "becomes mushy" from having been overstressed when trying to push the valve open. This is one of those instances where it would have made more sense, to me, to design with a long NON-braided cable. Someone once said, "You can't push a string," and even braided cable can become "string like" in places under the right (or, more accurately, wrong) conditions. Brian | ||
| Richard Greene Frequent User Username: benzjag Post Number: 243 Registered: 12-2012 |
I "think" my problem is indeed NOT the servo, BUT somehow the servo has been bypassed in the system! The blower fans work perfectly, BUT they are not adjustable! They blow on high even if the switch is on low, auto, high. Also, the defrost is not hot nor does it move the air to the screen. Again, I am thinking the servo is not getting power, etc. I loosen the cable at the tap and the lever moves freely (and both hoses are hot when heat is selected). The car "lived" in Florida all it's life after being bought at Bentley High Point;therefore, not any need for heat. I am assuming the heat was bypassed so the system would not adjust to heat on coolish mornings since the owner wanted AC all the time??? I bought the car from the original owner, but sadly, he passed away a year ago. Richard | ||
| Alan Dibley Frequent User Username: alsdibley Post Number: 337 Registered: 10-2009 |
In the last posting of the topic "Rolls Royce Air conditioning course notes - 1975", in this forum, are instructions on how to retrieve these a copy of this document. It might help you get to the cause of this problem. Good luck. Alan D. | ||
| Richard Greene Frequent User Username: benzjag Post Number: 244 Registered: 12-2012 |
I had the car shipped to my retired RR dealer tech. The servo is now working. It was a bad relay. The BAD news is the hoses to the heater core were disconnected because of a leaking heater core. I need to make a decision whether I want him to replace it. He said the dash has to be taken out and it's a 16 hour job (for labor). I'm tempted not to replace the core because everything is working perfectly now such as the cruise, etc. I am thinking if the dash is removed, I may be creating more problems! Any thoughts? Richard PS The car has been garaged from new and is in mint condition;therefore, I am disappointed with the news.   . | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 3245 Registered: 06-2009 |
Richard, Ultimately, only you can make that call. But be aware that the entire climate control system in this car depends on both heat and cooling sources at all times. You could almost certainly get away with no heat source, but I have no idea how that would impact the modulation of cooling in the cabin. The mixing flaps are used to get "the perfect temperature" in the air flow to maintain the cabin temperature where you set it. If your tech has done the heater core replacement in the past, I'd be less hesitant. Brian | ||
| Omar M. Shams Grand Master Username: omar Post Number: 2175 Registered: 04-2009 |
If it was me - I would try a well known fluid that is claimed to seal leaks in radiators to see if that seals the leak. If it works it will save you a lot of time and money. If it doesn't - you haven't lost anything. worth a try given how difficult it is to replace the heater matrix on these cars. | ||
| Jeff Young Frequent User Username: jeyjey Post Number: 457 Registered: 10-2010 |
That's a good idea. I've found them surprisingly effective.... | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 3246 Registered: 06-2009 |
Omar & Jeff, I'll give that suggestion a "third." In years past, when I had need to use radiator stop leak I found it very effective indeed. And if the issue was a tiny pin hole the end result often held for years afterward. There is very good reason to avoid tearing apart the entire dash unless that proves to be absolutely necessary. Brian | ||
| Richard Greene Frequent User Username: benzjag Post Number: 245 Registered: 12-2012 |
AWESOME idea using a sealer! Now, what are your recommendations for one that has worked for you? THANKS!!!!!!!!! | ||
| Peter Maclaren Experienced User Username: ludo Post Number: 55 Registered: 04-2009 |
'Bars Leaks" has proved very effective for me | ||
| Jeff Young Frequent User Username: jeyjey Post Number: 458 Registered: 10-2010 |
"Bars Leaks" is also the one I've used. That being said, I'd bet they're all pretty much the same stuff. | ||
| Mark Aldridge Frequent User Username: mark_aldridge Post Number: 761 Registered: 10-2008 |
Bars leaks has got me out of trouble numerous times, and was standard fit on some Jags from new. K Seal is popular these days in the trade in the UK but I have not used it. Mark | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 3247 Registered: 06-2009 |
Just as an aside, and I'm not proposing anyone use this rather than a real sealing product, my father (and many more than him) used to use ground black pepper. The concept was pretty much the same as "the real stuff" in that it allows very small particulate matter, that can float in the coolant and not harm the water pump, etc., to "find" the holes as coolant is being pushed out there and to plug them. Micro-corks, if you will. Most of the modern leak sealers for cooling systems and radiators in particular operate on this principle, and include some "solids" as part of what gets poured in. I'd imagine, though, that these solids have a bit more long term stability than black pepper powder would. Brian | ||
| Larry Kavanagh Frequent User Username: shadow_11 Post Number: 792 Registered: 05-2016 |
I've seen numerous DIY cooling system sealers used over the years and all of them sealed minor leaks to some extent but I'm not recommending them. They included: ground pepper, ground ginger and egg whites. I used the egg white once and it worked but after a while the smell of rotting egg was off-putting. I've seen a potato cut in half and rubbed on a windscreen to divert rain water when a wiper motor failed and that worked to some extent too. | ||
| Patrick Lockyer. Grand Master Username: pat_lockyer Post Number: 2482 Registered: 09-2004 |
I agree Larry. Sealers are a get you home temp fix can cause lasting problems if left in the system. A RR heater matrix and cooling rad etc will last years if the following is not carried out. First is the failing of antifreeze change in under five years due to the inhibitors failing. The added main cause that is present in most cooling systems is the electrolysis that eats away inside the rad, heater core (matrix) and sometimes liner seals water jacket etc due to the many types of metals present. More so with failing inhibitors. IMO a show queen in mint condition that spends it's time not used is the worst contender with the antifreeze left unchanged for years with the belief of chuck some sealant in when the coolant level has dropped leaving the stuff in. Water pump seals failing can be caused by the sealant being left in the system. Boiling due to a stuck thermostat and cooling radiator fins with internal blockage. The end in sight of a total wrecked engine. As for the heater matrix when holed I was always told to fit new and look for the cause. Time to get the volts meter out. | ||
| Graham Phillips Frequent User Username: playtime Post Number: 443 Registered: 03-2019 |
G'day everyone,.... Richard, there is nothing like doing the job correctly and fixing the heater core itself. You have a qualified guy who can do the job right so I would suggest you get it done right. Your car is as you say in mint condition so just keep it there. Love the picture, any more,.....? ;) Graham. | ||
| Richard Greene Frequent User Username: benzjag Post Number: 246 Registered: 12-2012 |
UPDATE! I have to apologize because my tech said the hoses were disconnected to the heater core because he was certain the heater core had a leak. I dropped the ball because he did NOT say it HAD a leak, but he was almost certain it did. Luckily, he was wrong! The hoses were reconnected & with the new relay, the servo/heat is working fine (with no leaks)! I drove the car 180 miles home yesterday with absolutely no problems! Again, I SINCERELY appreciate everyone's help! Richard | ||
| Jeff Martin Frequent User Username: jeff_r_1 Post Number: 309 Registered: 07-2018 |
Having the hoses disconnected was a good thing then, it saved the heater core from deteriorating because the last owner had no use for it. Most would have just left the coolant sitting in it with zero flow to it. | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 3248 Registered: 06-2009 |
The problem being that, in the SY2 series cars (and I think even the SY1, but I could be wrong about that), the climate control system always cools down air to remove humidity if the temperature is above freezing and then reheats it (even if just a bit) afterward. If the climate control is used at all in these cars both the heat and ac parts of the heat exchanger (AKA heater core) should be getting a frequent workout. I have no idea why someone would have disconnected the flow to the heater part of the heat exchanger, to be honest. Brian | ||
| Richard Greene Frequent User Username: benzjag Post Number: 247 Registered: 12-2012 |
Agree, Brian. I do not understand why someone would have disconnected the hoses! Graham...Attached are some pics of what I did to the large "hole" between the seats (used originally for cassette/8-track tapes). I used a console from a Mercedes. I dyed the console to match the seats. Richard   | ||
| Graham Phillips Frequent User Username: playtime Post Number: 444 Registered: 03-2019 |
G'day everyone,... Richard, Great news with the heater, best outcome there. Thats not a bad job you have done with the center console. Graham. | ||
| Patrick Lockyer. Grand Master Username: pat_lockyer Post Number: 2483 Registered: 09-2004 |
That is good news in more ways than one re sealant! "I have no idea why someone would have disconnected the flow to the heater part of the heat exchanger, to be honest." To answer the above maybe the a/c controller or failed relay could have could have caused it to fail in the open hot position, not a good thing in a hot climate  | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 3249 Registered: 06-2009 |
Patrick, Not some thing I'd considered, but it would be an absolutely reasonable presumption. I wouldn't have disconnected them, but instead put a manual cut-off valve in. People in the warmer climes here in the USA are "freezing" in weather that I'm still outside in short sleeves for, and that occurs in places like Georgia, Florida, etc. during the driving season for these cars. But desperate times call for desperate measures and some don't really think about all the ramifications. Brian |
