jzar
10-12-2009, 05:22 PM
1983 p-type
I've been reading and searching. I've done the following:
Replaced Water Valve
Checked for leaks
Burped the radiator
Made sure the fluid is full
I get heat to the core, both hose's heat up.
I checked all fuses...all good
I did the first part of the Functional Test
from the trouble shooting TSRM Guide for the heater
INCORRECT TEMPERATURE OUTPUT:
Control Cable broken or binding
--since the power servo wont work I can't check this....afaik
Heater hoses leaking or clogged,
-they all seem good. I've not taken them all apart nor flushed them with water. No leaks, I've checked for that.
Water Valve faulty, -replaced with new unit from toyota
Air Dampers Broken,
-unknown
Air Ducts Clogged,
-since I have no heat whatsoever seems unlikey...I just replaced the blower and checked those ducts I could see and blew out with air what I could.
Heater Radiator leaking or clogged,
-new radiator. Flush system when installed
Heater control unit faulty,
-yeah....most likely but what part?
I connected to the check connector of the amplifier, I put the temp control lever to 77. I had clicking and movement of the power servo stem. THE TSRM says this is a vacumm leak
I have not.....
checked the vacuum circuit for leaks...excect for a quick cursory look and listen.
From my reading here that clicking seems to fall into this..
This is a common problem with Mk2's. The noise is from the relays that control the heater valve actuator (the gold thing behind the radio). The slide resistors in the heater controls can wear out, and have bad internal connections with the sliding arms (levers). Basically, one second they would send a voltage signal to the actuator circuits, turning on a relay, and the next, the internal connection would break, the voltage signal would go away, and the relay would click back off. The signal can change very rapidly due to road vibration, or whatever, and that change between on and off can wreak havoc on the relay systems back there. The noise can be really annoying, especially if you are cold and the heater just wants to make noise, and not heat!
As soon as I replaced all those switches the noises pretty much stopped, and the heater works just fine. Major PITA job, but worth it.
All this crap could have been avoided if Toyota had just given our cars cable controlled manual heater valves like every other car, but then we couldn’t have had "Automatic Air Conditioning". But luckily, the Supra is *not* like every other car, and I love it!
Vern
So I wonder if I should look at the heater control itself before I search for vacuum leaks.
I've got a spare heater level, it was from an unknown donor car. Should I do a clean up and try the spare or try and see if there is a new part still available?
Jim King also had this to say.....
The fan in the console draws in air to read the cabin temperature.
There is a thermistor just in front of it.
Along with it, the outside temperature sensor, the solar sensor and a few other water temp sensors and relays provides the data. Note the test connector bypasses all of this.
With this data, the temp lever selection, the AC amplifier 'tries' to keep the cabin temperature at a consistent level.
If fact, having this thermistor at the back of the console is a very good idea, as most are located in the dash, which doesn't give that accurate of a read.
The mystery is why the AC amplifier continues to send a small voltage to DVV, located left and behind the radio. It's a vacuum valve driven by magnetic relays. The relays are generating the clicking.
I tried a new factory amplifier and it still clicked.
Based on the circuit, a *very* small vacuum leak would cause the servo to slid right, sending a new resistance value to the amplifier. So, if either the servo or DVV was leaking, this could be a cause.
However, if it were a consistent vacuum leak, it would do this *all* the time.
One test I would like to see is with a MK2 that clicks, and try pulling vacuum against the servo. Increased by small amounts, because it could be possible the rubber diaphragm is leaking at a certain point. Same could be with the DVV.
I do know they switched to electric servo motors in later Toyotas.
Vern does not say that he bought new switches but I'm going to assume that is what he did. I'm also guessing that the temperture lever is the only one that needs to be replaced as it is the only one that sends a signal to the power servo.
Its all bit confusing but that clicking Vern speaks of is exactly what I get. I can see the power servo not being able to move correctly in time with those clicks. Any input or help would help.
Should I try to replace that heater temp lever with new and go from there? I really don't know which relay Vern was replacing. I am very unsure of what to replace or check for the relays...
I've been reading and searching. I've done the following:
Replaced Water Valve
Checked for leaks
Burped the radiator
Made sure the fluid is full
I get heat to the core, both hose's heat up.
I checked all fuses...all good
I did the first part of the Functional Test
from the trouble shooting TSRM Guide for the heater
INCORRECT TEMPERATURE OUTPUT:
Control Cable broken or binding
--since the power servo wont work I can't check this....afaik
Heater hoses leaking or clogged,
-they all seem good. I've not taken them all apart nor flushed them with water. No leaks, I've checked for that.
Water Valve faulty, -replaced with new unit from toyota
Air Dampers Broken,
-unknown
Air Ducts Clogged,
-since I have no heat whatsoever seems unlikey...I just replaced the blower and checked those ducts I could see and blew out with air what I could.
Heater Radiator leaking or clogged,
-new radiator. Flush system when installed
Heater control unit faulty,
-yeah....most likely but what part?
I connected to the check connector of the amplifier, I put the temp control lever to 77. I had clicking and movement of the power servo stem. THE TSRM says this is a vacumm leak
I have not.....
checked the vacuum circuit for leaks...excect for a quick cursory look and listen.
From my reading here that clicking seems to fall into this..
This is a common problem with Mk2's. The noise is from the relays that control the heater valve actuator (the gold thing behind the radio). The slide resistors in the heater controls can wear out, and have bad internal connections with the sliding arms (levers). Basically, one second they would send a voltage signal to the actuator circuits, turning on a relay, and the next, the internal connection would break, the voltage signal would go away, and the relay would click back off. The signal can change very rapidly due to road vibration, or whatever, and that change between on and off can wreak havoc on the relay systems back there. The noise can be really annoying, especially if you are cold and the heater just wants to make noise, and not heat!
As soon as I replaced all those switches the noises pretty much stopped, and the heater works just fine. Major PITA job, but worth it.
All this crap could have been avoided if Toyota had just given our cars cable controlled manual heater valves like every other car, but then we couldn’t have had "Automatic Air Conditioning". But luckily, the Supra is *not* like every other car, and I love it!
Vern
So I wonder if I should look at the heater control itself before I search for vacuum leaks.
I've got a spare heater level, it was from an unknown donor car. Should I do a clean up and try the spare or try and see if there is a new part still available?
Jim King also had this to say.....
The fan in the console draws in air to read the cabin temperature.
There is a thermistor just in front of it.
Along with it, the outside temperature sensor, the solar sensor and a few other water temp sensors and relays provides the data. Note the test connector bypasses all of this.
With this data, the temp lever selection, the AC amplifier 'tries' to keep the cabin temperature at a consistent level.
If fact, having this thermistor at the back of the console is a very good idea, as most are located in the dash, which doesn't give that accurate of a read.
The mystery is why the AC amplifier continues to send a small voltage to DVV, located left and behind the radio. It's a vacuum valve driven by magnetic relays. The relays are generating the clicking.
I tried a new factory amplifier and it still clicked.
Based on the circuit, a *very* small vacuum leak would cause the servo to slid right, sending a new resistance value to the amplifier. So, if either the servo or DVV was leaking, this could be a cause.
However, if it were a consistent vacuum leak, it would do this *all* the time.
One test I would like to see is with a MK2 that clicks, and try pulling vacuum against the servo. Increased by small amounts, because it could be possible the rubber diaphragm is leaking at a certain point. Same could be with the DVV.
I do know they switched to electric servo motors in later Toyotas.
Vern does not say that he bought new switches but I'm going to assume that is what he did. I'm also guessing that the temperture lever is the only one that needs to be replaced as it is the only one that sends a signal to the power servo.
Its all bit confusing but that clicking Vern speaks of is exactly what I get. I can see the power servo not being able to move correctly in time with those clicks. Any input or help would help.
Should I try to replace that heater temp lever with new and go from there? I really don't know which relay Vern was replacing. I am very unsure of what to replace or check for the relays...