AC poor vent flo
06-21-2019, 03:49 PM
#2
Tech Contributor
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Location: Anthony TX
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CI 6,7,8,9,11 Vet
St. Jude Donor '08
NO FILTER on a C5.
The air flow through the vents is controlled by vacuum actuated damper doors. If you don't have the proper vacuum signal, the damper doors will relax and the air will flow out of multiple vents especially the defrost.
The vacuum signal originates at the back of the intake manifold, down to the passengers fender and into the cabin to the HVAC vacuum control module. Check for broken /cracked chewed nylon vacuum lines
The air flow through the vents is controlled by vacuum actuated damper doors. If you don't have the proper vacuum signal, the damper doors will relax and the air will flow out of multiple vents especially the defrost.
The vacuum signal originates at the back of the intake manifold, down to the passengers fender and into the cabin to the HVAC vacuum control module. Check for broken /cracked chewed nylon vacuum lines
06-21-2019, 04:45 PM
#3
Melting Slicks
Member Since: Nov 2014
Location: Havre de Grace Maryland
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Follow Bill Curlee's suggestion. Here is another process you can try that just may work. It did for me when I had a similar issue a few years ago. No further issues.
Do the fuse #27 re calibration--turn driver side temp dial to 60, pass side to straight up 12 o clock, ignition off, pull fuse 27 passenger side fuse box, wait no less than 60 full seconds, replace fuse and listen to hear the actuator doors re-calibrating, run ac system at the temps set and see if you don't get cold air both sides.
With summer upon us, you want A/C. Hope you resolve.
Do the fuse #27 re calibration--turn driver side temp dial to 60, pass side to straight up 12 o clock, ignition off, pull fuse 27 passenger side fuse box, wait no less than 60 full seconds, replace fuse and listen to hear the actuator doors re-calibrating, run ac system at the temps set and see if you don't get cold air both sides.
With summer upon us, you want A/C. Hope you resolve.
06-21-2019, 10:21 PM
#4
The AC has a vacuum line that runs from the passenger side firewall grommet (coming in from the many lines inside the cabin from the vacuum-controlled vents in the dash), to underneath the battery tray, and meets the Air Pump System's line into the PCM spot in the bottom of the passenger fender well. They all meet and join at a vacuum canister. There is also another line that goes from this canister to the back of the intake manifold: the main source of vacuum.
Those lines are a hard very brittle plastic that break over time.
Really, if ANY of those connections, (probably totaling more than 10 feet of it, including ANY of the connections in the dash) can break in one or more spots and cause vacuum leaks, thus weakening the air blowing out of the vents. As stated by Bill, check to see if you can select different vents on the AC unit. If they blow out all of the vents, you have a leak or broken vents. If you can change the vent selection, you might still have a leak, but minor.
Most of those vacuum lines are hidden. They are wrapped up in electrical wires, underneath a conduit, and electrical tape. It was a large pain indeed.
Those lines are a hard very brittle plastic that break over time.
Really, if ANY of those connections, (probably totaling more than 10 feet of it, including ANY of the connections in the dash) can break in one or more spots and cause vacuum leaks, thus weakening the air blowing out of the vents. As stated by Bill, check to see if you can select different vents on the AC unit. If they blow out all of the vents, you have a leak or broken vents. If you can change the vent selection, you might still have a leak, but minor.
Most of those vacuum lines are hidden. They are wrapped up in electrical wires, underneath a conduit, and electrical tape. It was a large pain indeed.
Last edited by 02torchred; 06-21-2019 at 10:24 PM.
06-22-2019, 05:49 AM
#5
Burning Brakes
The AC has a vacuum line that runs from the passenger side firewall grommet (coming in from the many lines inside the cabin from the vacuum-controlled vents in the dash), to underneath the battery tray, and meets the Air Pump System's line into the PCM spot in the bottom of the passenger fender well. They all meet and join at a vacuum canister. There is also another line that goes from this canister to the back of the intake manifold: the main source of vacuum.
Those lines are a hard very brittle plastic that break over time.
Really, if ANY of those connections, (probably totaling more than 10 feet of it, including ANY of the connections in the dash) can break in one or more spots and cause vacuum leaks, thus weakening the air blowing out of the vents. As stated by Bill, check to see if you can select different vents on the AC unit. If they blow out all of the vents, you have a leak or broken vents. If you can change the vent selection, you might still have a leak, but minor.
Most of those vacuum lines are hidden. They are wrapped up in electrical wires, underneath a conduit, and electrical tape. It was a large pain indeed.
Those lines are a hard very brittle plastic that break over time.
Really, if ANY of those connections, (probably totaling more than 10 feet of it, including ANY of the connections in the dash) can break in one or more spots and cause vacuum leaks, thus weakening the air blowing out of the vents. As stated by Bill, check to see if you can select different vents on the AC unit. If they blow out all of the vents, you have a leak or broken vents. If you can change the vent selection, you might still have a leak, but minor.
Most of those vacuum lines are hidden. They are wrapped up in electrical wires, underneath a conduit, and electrical tape. It was a large pain indeed.
I had a vac line cracked inside a wire loom (impossible to locate), so I ran a new line all the way to the vac reservoir inside the passenger side fender. Worked like a charm.