Subject: Vacuum Tests From: Wally Plumley Date: Tue, 19 Oct 1999 10:39:27 -0400 X-Message-Number: 17 >> I'm getting a constant flow of warm air out of my side vents at all temp. settings.I've replaced the heater valve,but the problem persists.I assume it's a vacuum problem...what should I look at first? Tia Rich '81 5 speed << This is a generalized vacuum test. Your system may vary from this. BTW, we sell an inexpensive kit that includes the proper 4-way connector, check valve and lines. 1) Set the temp lever to the minimum temp. Pull the vacuum line off of the heater valve, and crank the engine. Vacuum closes the valve, so you should have strong vacuum at the disconnected hose. If not, reconnect the hose and go to step 2). 2) Pull the hose off of the inlet side of the vacuum check valve located near the brake booster. There should be a strong vacuum. If not, trace the line back and check for a disconnected or collapsed line. If there is a strong vacuum, reconnect the check valve and pull the line off of the other end. There should be the same level of vacuum at the valve connection. If not, either clean the check valve with spray carb cleaner and low-pressure compressed air, or replace it. If there is a strong vacuum, go to step 3). 3) Carefully check the rubber 4-way connector for leaks. If any are found, repair or replace the connector. If no leaks are found, go to step 4). 4). Find the vacuum line that disappears into the fender, and the line that goes the other way and disappears into the firewall. Pull the line off that runs to the firewall. There should be a strong vacuum at the 4-way connector. If not, pull the line off that disappears into the fender and plug that opening on the connector. Recheck the vacuum level on the connector that goes to the firewall. If the vacuum increased, remove the fender liner and check the vacuum reservoir and its lines. Repair or replace as required. If there is good vacuum, reconnect everything and go to the next section. Remove the carpeted panel from both sides of the center console. Locate the vacuum manifold. It has six colored vacuum lines attached. If possible, get a vacuum tester, such as a MityVac hand pump. (Given the number of vacuum problems you will face over the years, I would suggest buying a MityVac.) If you can't get a tester or pump of any kind, you can use the self-contained oral vacuum source (put it in your mouth and suck). Remove and test one line at a time, replacing each line before removing the next. The lines are: A - Yellow - Footwell Flap B - Green - Defroster Flap C - Orange - Center Nozzle Stage One D - Brown - Center Nozzle Stage Two E - Red - Mixing Flap and Heating Valve F - Blue -Fresh Air Bypass Flap The Red line is the most likely suspect if it is a vacuum problem. If the problem is not a simple vacuum problem, check pages 87-104 and up in Volume IV of the shop manuals for the A/C troubleshooting. The setting motor (temp control motor) and the heater valve are two likely suspects. Wally Plumley 928 Specialists