Series I L27 (1992-1994 SE,SLE, SSE) & Series II L36 (1995-1999 SE, SSE, SLE) and common problems for the Series I and II L67 (all supercharged models 92-99) Including Olds 88's, Olds LSS's, Olds 98 91-96, Buick Lesabres and Park Avenue 91-96. Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.
My Bonneville has low air flow with the AC, and since I've only recently started using the heater, I discovered that with the heater on, I get hot air flow out the floor vents, but the top vents seem to be leaking in cold, outside air. The latter really bothers me because my morning commute consists of getting toasty feet and frozen knees.
This to me sounds like some vent somewhere is not closing fully, but I have no clue what to look for or where.
I have the electronic climate control system. Any ideas?
tl;dr
Low flow A/C in summer, hot air from floor and cold air from vents with heater in winter.
a classic symptom of loss of vacuum to the HVAC controller module is air flow to floor and windshield defroster vents instead of to dash vents when selected. if you want to check out this possibility, the vacuum line for the HVAC originates at a tee off the intake manifold. follow the brake booster vacuum line to the tee and then look for a small plastic line leaving the tee and entering a small metal box on the firewall (vacuum resivoir). sometimes the vacuum line will deteriorate at this junction. if ok, follow the vacuum line to the passenger side of the firewall where it will enter the firewall along with wiring.
if vacuum is ok to this point, you will most likely find the problem at the vacuum connector on the HVAC controller. again, a common problem with the vacuum lines leaving the HVAC controller is collapse of the lines going to the various vent controller motors. a classic solution is to find plastic tubing that will fit both HVAC vacuum output lines and the lines going to the vent controllers. bridge the HVAC controller lines to the lines going to the vent controllers.
this may not be the problem as it doesn't affect volume of air flow which you state is low. one cure for the low air flow is clogged evaporator. there is a procedure in this forum for cleaning evap.
Last edited by gmman on Mon Dec 03, 2012 2:23 pm, edited 1 time in total.
I cleaned out the evaporator per the procedure here last summer. It didn't make any difference in the air flow, which was surprising.
I will look into the vacuum lines because if they're anything like some of the other old plastic lines, they're brittle and could have tiny cracks in them after 20 years. Nothing lasts forever, that's why God invented the toolbox.
I am having the same issue with my 97 SSEi
On high the air barely flows out- I did the core cleaning task twice with no difference
I have replaced the blower, blower cover, blower hose and resistor pack
On another note the air from the two drivers side vents are cold but the two passenger side vents seem warmer
the heat also does not work
