AC problems for the Devek 6liter street car - little guidance?
07-19-2016, 05:08 PM
#1
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AC problems for the Devek 6liter street car - little guidance?
i havent cracked the manuals yet for the troubleshooting, and i have basic knowldege of how the system works, BUT...........
the owner Greg, of the Devek 6 liter street car is trying to diagnose his AC problems. bought a used compressor, and that leaked so he bought a new one and it started to cool things down, but then was blowing fuses. some say that the control head might be the problem.. if i jumper that relay under the base of the windshield cover, nothing happens. if he puts 12v to the compressor, the clutch goes on and it blows cool, but he doesn't want to rig that with a switch.
he was thinking he has too much oil in the system. dont know if that is possible..he bought some R12 and is using that.
any ideas of what to look for next?
the owner Greg, of the Devek 6 liter street car is trying to diagnose his AC problems. bought a used compressor, and that leaked so he bought a new one and it started to cool things down, but then was blowing fuses. some say that the control head might be the problem.. if i jumper that relay under the base of the windshield cover, nothing happens. if he puts 12v to the compressor, the clutch goes on and it blows cool, but he doesn't want to rig that with a switch.
he was thinking he has too much oil in the system. dont know if that is possible..he bought some R12 and is using that.
any ideas of what to look for next?
07-19-2016, 06:31 PM
#5
Under the Lift
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i havent cracked the manuals yet for the troubleshooting, and i have basic knowldege of how the system works, BUT...........
the owner Greg, of the Devek 6 liter street car is trying to diagnose his AC problems. bought a used compressor, and that leaked so he bought a new one and it started to cool things down, but then was blowing fuses. some say that the control head might be the problem.. if i jumper that relay under the base of the windshield cover, nothing happens. if he puts 12v to the compressor, the clutch goes on and it blows cool, but he doesn't want to rig that with a switch.
he was thinking he has too much oil in the system. dont know if that is possible..he bought some R12 and is using that.
any ideas of what to look for next?
the owner Greg, of the Devek 6 liter street car is trying to diagnose his AC problems. bought a used compressor, and that leaked so he bought a new one and it started to cool things down, but then was blowing fuses. some say that the control head might be the problem.. if i jumper that relay under the base of the windshield cover, nothing happens. if he puts 12v to the compressor, the clutch goes on and it blows cool, but he doesn't want to rig that with a switch.
he was thinking he has too much oil in the system. dont know if that is possible..he bought some R12 and is using that.
any ideas of what to look for next?
You need to look at the wiring diagrams for his model year. So first verify the 14-pin connector has continuity, then jumper the pressure switch plug. If that works, then either the pressure is too low (undercharged) or the pressure switch is defective. If not, work back from there.
07-19-2016, 06:37 PM
#6
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OK, so it works when 12V is given directly to the compressor clutch. So, you need to work back from there to find where the electrical failure point is. 14-pin connector (pin 9 in my 89) near the jump post to low/high pressure switch, through the CE panel (M12 to M15 in my 89) to freeze switch (you called it a relay) to pin 2 on connector T29 near the head unit, to the head unit relay.
You need to look at the wiring diagrams for his model year. So first verify the 14-pin connector has continuity, then jumper the pressure switch plug. If that works, then either the pressure is too low (undercharged) or the pressure switch is defective. If not, work back from there.
You need to look at the wiring diagrams for his model year. So first verify the 14-pin connector has continuity, then jumper the pressure switch plug. If that works, then either the pressure is too low (undercharged) or the pressure switch is defective. If not, work back from there.
The way that car is rigged together, maybe he just needs a toggle switch on the dash saying, "cold".
07-19-2016, 11:05 PM
#7
Wally to the rescue
Particularly,
Particularly,
TROUBLESHOOTING THE A/C COMPRESSOR CLUTCH ELECTRICAL SYSTEM
If the A/C compressor clutch does not engage, remove the plastic shield from the rear of the engine compartment, and find the antifreeze switch. With the ignition switch on and the A/C on max cool, test for 12 vdc on both of the switch terminals. If there is no power on either terminal, the most likely problem is the small relay in the control head. If there is power on only one terminal, the switch is either bad or misadjusted. If there is power on both switch terminals, go to the refrigerant pressure switch.
With the ignition switch on, and the A/C on max cool, reach in thru the front grille, pull the wire harness from the refrigerant pressure switch, and check for 12 vdc at the terminals in the wire harness - there should be 12 vdc on one of the terminals. If there is power here, temporarily jumper the wire harness terminals together. The compressor clutch should then operate. If it does, the refrigerant pressure is probably low. Do not operate the system longer than required for troubleshooting and charging with the low pressure switch by-passed! Doing so can very easily destroy the compressor thru lack of lubrication.
If the clutch does not operate, stop the engine, then turn the ignition back on, but DO NOT crank the engine. Test for 12 vdc at the clutch connector. If there is no power here, the wire between the pressure switch and the clutch is probably bad. If there is power here, but the clutch doesn’t work, check the ground connection. If everything appears to be OK, the clutch may be bad, or the relay may not be furnishing enough power to operate the clutch. One test is to use any 12 vdc device that pulls several amps as a tester. This can be a headlamp bulb, blower motor, etc. If the device appears to be receiving insufficient power, the relay is suspect.
If the A/C compressor clutch does not engage, remove the plastic shield from the rear of the engine compartment, and find the antifreeze switch. With the ignition switch on and the A/C on max cool, test for 12 vdc on both of the switch terminals. If there is no power on either terminal, the most likely problem is the small relay in the control head. If there is power on only one terminal, the switch is either bad or misadjusted. If there is power on both switch terminals, go to the refrigerant pressure switch.
With the ignition switch on, and the A/C on max cool, reach in thru the front grille, pull the wire harness from the refrigerant pressure switch, and check for 12 vdc at the terminals in the wire harness - there should be 12 vdc on one of the terminals. If there is power here, temporarily jumper the wire harness terminals together. The compressor clutch should then operate. If it does, the refrigerant pressure is probably low. Do not operate the system longer than required for troubleshooting and charging with the low pressure switch by-passed! Doing so can very easily destroy the compressor thru lack of lubrication.
If the clutch does not operate, stop the engine, then turn the ignition back on, but DO NOT crank the engine. Test for 12 vdc at the clutch connector. If there is no power here, the wire between the pressure switch and the clutch is probably bad. If there is power here, but the clutch doesn’t work, check the ground connection. If everything appears to be OK, the clutch may be bad, or the relay may not be furnishing enough power to operate the clutch. One test is to use any 12 vdc device that pulls several amps as a tester. This can be a headlamp bulb, blower motor, etc. If the device appears to be receiving insufficient power, the relay is suspect.
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07-20-2016, 02:21 PM
#8
Rennlist Member
Sounds like a typical failure of the relay in the control head- by now they are all failure candidates. Mine has a mind of its own working one minute and cutting out the next and switching the thing off and then back on seems to get a temporary result.
The system is actually quite simple and providing it holds gas [no small feat on these cars] you need to get battery voltage to the clutch solenoid and for this to happen the relay has to work, the freeze switch has to work and the low gas pressure switch has to be healthy and that is about it really system wise.
Regards
Fred
The system is actually quite simple and providing it holds gas [no small feat on these cars] you need to get battery voltage to the clutch solenoid and for this to happen the relay has to work, the freeze switch has to work and the low gas pressure switch has to be healthy and that is about it really system wise.
Regards
Fred
07-21-2016, 07:30 AM
#10
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07-21-2016, 01:13 PM
#12
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07-21-2016, 02:07 PM
#13
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It's not really. Pull out the center vents, pop off the little H-shaped spacer thingy and unscrew the (4?) screws. Then the HVAC head pulls out, and you can disconnect the electrical stuff.
I would work backwards from under the hood, however. You have to take the HVAC head apart to find the relay, and all of that plastic stuff is prone to breakage. A lot easier to see if you have 12V at the various points described above. If you do, the problem is not your HVAC head.
I would work backwards from under the hood, however. You have to take the HVAC head apart to find the relay, and all of that plastic stuff is prone to breakage. A lot easier to see if you have 12V at the various points described above. If you do, the problem is not your HVAC head.
07-21-2016, 02:25 PM
#14
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all i remember is when take things out, making race cars, its not pretty.
however, on his car, i do remember most of the vacuum lines being broken too!
however, on his car, i do remember most of the vacuum lines being broken too!
07-21-2016, 02:32 PM
#15
You don't have to pull the unit to see if the relay is functioning correctly. You can audibly hear it 'click' when you depress the AC button. You don't even have to depress the button so it stays down... just enough for the switch to trip the relay.
For example, you can hold the switch just before the detent, and close the circuit, and hear the relay turn on and off. That way you don't fool yourself thinking the detent spring is actually the relay.
All this should be done with the key in the 'on' position, but the car not running. One of the radiator fans will also kick on and the louvers will cycle when the AC is on and the compressor has voltage.
For example, you can hold the switch just before the detent, and close the circuit, and hear the relay turn on and off. That way you don't fool yourself thinking the detent spring is actually the relay.
All this should be done with the key in the 'on' position, but the car not running. One of the radiator fans will also kick on and the louvers will cycle when the AC is on and the compressor has voltage.