Air Conditioning questions
05-24-2010 | 07:41 PM
#1
Thread Starter
Member
SL Member
Joined: Oct 2004
Posts: 70
Air Conditioning questions
Hi all-
This is not to rehash issues of underpowered a/c’s in the 1st gen’s but to compare notes for service and diagnostics.
In my 2004 with 90,000 miles the a/c now only works (feebly 58°) on the two lowest settings and fails to cool on the two higher settings. At start up, the two higher settings might sometimes start to cool (temp drops to 58°) but when the vehicle reaches operating temperature the cooling stops and won’t restart.
The lower settings will usually puff cool continuously for extended periods (58°) and only on occasion have paused cooling, but then resume with the feeble chill.
Belts are new; battery is new; antifreeze is topped up (was low); 134a is at pressure not over or under.
As the system has the ability to cool somewhat it does not seem to be a leak in the evaporator, condenser etc.
I suspect that that the issue is electrical as it is the electrical control settings that are the differentiating item.
So here are the questions:
-Does someone have a wiring diagram of the a/c system? If the a/c is valve actuated, instead of clutch, does it have two settings with a low for defrost and low service and high for serious cooling? Are there other sensors or switches external to the compressor that are subject to confusion?
-With the TSB retrofits did a different/larger compressor get used as a substitute or was that just dealer mythology? Anyone have part numbers? If, in the end, I have to go with a replacement then I might as well go with a more robust unit.
-Has anyone had experience with any a/c repair shops in the Boston, MA area? So far the non-dealer dudes of some local reputation are saying “haven’t seen any of those yet; where’s the fuse?”: and the dealers’ service technicians are all hidden behind the blank-stare-service-writers who appear congenitally unable to discuss the matter.
As we are getting on with miles I suspect this will be more of an issue for many of us.
-Thanks
This is not to rehash issues of underpowered a/c’s in the 1st gen’s but to compare notes for service and diagnostics.
In my 2004 with 90,000 miles the a/c now only works (feebly 58°) on the two lowest settings and fails to cool on the two higher settings. At start up, the two higher settings might sometimes start to cool (temp drops to 58°) but when the vehicle reaches operating temperature the cooling stops and won’t restart.
The lower settings will usually puff cool continuously for extended periods (58°) and only on occasion have paused cooling, but then resume with the feeble chill.
Belts are new; battery is new; antifreeze is topped up (was low); 134a is at pressure not over or under.
As the system has the ability to cool somewhat it does not seem to be a leak in the evaporator, condenser etc.
I suspect that that the issue is electrical as it is the electrical control settings that are the differentiating item.
So here are the questions:
-Does someone have a wiring diagram of the a/c system? If the a/c is valve actuated, instead of clutch, does it have two settings with a low for defrost and low service and high for serious cooling? Are there other sensors or switches external to the compressor that are subject to confusion?
-With the TSB retrofits did a different/larger compressor get used as a substitute or was that just dealer mythology? Anyone have part numbers? If, in the end, I have to go with a replacement then I might as well go with a more robust unit.
-Has anyone had experience with any a/c repair shops in the Boston, MA area? So far the non-dealer dudes of some local reputation are saying “haven’t seen any of those yet; where’s the fuse?”: and the dealers’ service technicians are all hidden behind the blank-stare-service-writers who appear congenitally unable to discuss the matter.
As we are getting on with miles I suspect this will be more of an issue for many of us.
-Thanks
05-24-2010 | 08:17 PM
#2
Member
SL Member
Joined: Feb 2007
Posts: 50
From: Sylva, NC
Here's a link to the TSB if you don't have it already:
http://tijil.org/Scion_TSBs/ac00704r.pdf
Unfortunately I don't have any personal knowledge of the problem.
http://tijil.org/Scion_TSBs/ac00704r.pdf
Unfortunately I don't have any personal knowledge of the problem.
05-29-2010 | 03:54 AM
#3
Thread Starter
Member
SL Member
Joined: Oct 2004
Posts: 70
An update for those that care; After reading the TSB a few times I opted to go to the dealership. They couldn’t find anything wrong, confirmed that the pressure was near normal but a little low and that they could not find any leaks or electrical faults. They did a system evacuation and refill and injected dye. Their instruction is to drive it for several weeks and to come in for an evaluation to see if there is a minor leak.
The immediate result of the evacuation and refill is that the A/C blows at 52° instead of 58° and doesn’t cycle off.
If this is fixed, only time will tell.
The immediate result of the evacuation and refill is that the A/C blows at 52° instead of 58° and doesn’t cycle off.
If this is fixed, only time will tell.
06-14-2010 | 04:29 AM
#6
Thread Starter
Member
SL Member
Joined: Oct 2004
Posts: 70
The TSB didn’t refer to any thermometers/thermostats as part of the diagnostic. It doesn’t mean that there isn’t one but I agree that a person would think that that would be the first thing to check.
It’s now two weeks since the dealers service procedure and the a/c is performing as good as it ever has.
Certainly there isn’t a fast leak, time will show if there is a slow leak.
The curious thing is that the pressure checks showed good pressure or perhaps only marginally low pressure. I suspect that the internal valves instead of clutch have a way of hiding low pressure if there is not a full charge to operate the system.
The TC has an electric clutch system if I recall, which would certainly indicate that checking any thermostats to be prudent.
It’s now two weeks since the dealers service procedure and the a/c is performing as good as it ever has.
Certainly there isn’t a fast leak, time will show if there is a slow leak.
The curious thing is that the pressure checks showed good pressure or perhaps only marginally low pressure. I suspect that the internal valves instead of clutch have a way of hiding low pressure if there is not a full charge to operate the system.
The TC has an electric clutch system if I recall, which would certainly indicate that checking any thermostats to be prudent.
Thread
Thread Starter
Forum
Replies
Last Post
