Well I have updates. The blower motor I received did not move any airflow at all. Looked closely at it and ended up reversing the wiring connection. Started moving a bit of airflow. It is getting returned. Incedentally I think I discovered the issue with the other blower motor. The ground terminal even though the screw was tight was not making a good connection. I never put much thought into it because even the OEM blower I removed off this van had a painted surface under the connection. I threw a wire brush in my drill and cleaned the paint off where the ground connects. Put the old blower motor back in and now get right at 14 mph out of the dash vents before the blower motor and alternator heated up, then dropped to about 13.4-13.5 with it heat soaked. It is a noticeable improvement and a step in the right direction. I do need to seal up the duct work at some point. I tried starting and stopping the blower several time and it worked every time. I may order the standard GM blower for this van as a backup. Lesson learned, rotation direction matters in the blower case, regardless if the wheel is designed to work with the reversed rotation.
It was about as nasty today as the typical Texas weather gives in terms of relative heat from temperature and humidity. It was 102F in the shop and 46% relative humidity, real feel of 113F. I bumped the idle up to ~1,350 rpm and re-checked the a/c charge. Ended up adding about 6-8oz more refrigerant to drop the superheat down to the 7-9F range. With a properly chilled evaporator core the vent temps are now much more consistent across the whole dash where there was an 8-10F difference with the right hand most vent being the coldest before. Was running at 30/265 psi, center vent was holding ~40F. At the normal 850 rpm idle after 5 minutes was holding 37/270 psi with 48F out of the vents. At idle, the 12" condenser pusher fan I recently fitted dropped the pressures about 5 psi on the low side and 15-20 psi on the high side when I plugged the relay in. It dropped to about 45F out of the vents. Not a huge change but I will take all I can get in this Texas heat. I brought the engine up to 2,000 rpm then 2,500 rpm, the compressor ran continuously and the temps dropped to the mid-low 30s out of the vents. I can tell it is going to be a noticeable improvement in cooling when it is running dowm the road at highway speed as well.
Ended up doing the CFM calculation on the mechanical fan as well with everything well heat soaked. It was holding fairly steady at around 8 mph average. Using the area of the condenser, calculated a bit over 2,600 cfm across the condenser area in front of the grille. Not perfect but close enough. Its more than a pair of over-rated in free flow, 3,000 cfm electric fans would move when the motors heat up. That CFM is airflow through the cooling stack with whatever airflow losses are present vs free-air like electric fans are jokingly rated.
Wire brushed ground connection. Might be worth trying out on these under performing blowers.
You must be registered for see images attach
A couple of clips I made while working with it.
xc_hide_links_from_guests_guests_error_hide_media
