Thar she blows! (HVAC blower night & day.)

[BullnoseLuvr]

I don't know if we ever full crawl out of the rabbit hole but I was meaning that my system is the same as new so the test should be comparible.

I can also test without the relay for comparison on the same truck. Then throw in the ground relay and we can compare all of it.

Honestly never knew such a device existed. Glad you showed it.

I got mine to balance my central A/C. Now that was a rabbit hole.

I can't believe what a difference just cleaning the debris and replacing the evaporator made. I assume it's performing basically as it was new, though I'm still going to check for voltage drop at the motor.

Mark

[Gary Lewis]

So I measured my airflow with the engine at 1500 rpm, all accessories off and controls on MAX A/C with no compressor since the system isn't finished yet. These numbers are meaningless since I didn't take "before" measurments but they might be of interest to the next person who measures his truck vent airflow with an anemometer. The pics are the vents left to right in two passes, 8 pics total. I apologize for the sidewaysness but I'm just not up to rotating the pics.

Mark

I'm confused - why two sets of pics? What changed?

Also, is the air speed in FPM or what?

[kramttocs]

I'm still going to check for voltage drop at the motor.

Great. I know Gary measured a pretty significant drop when he did the test.

 

[Gary Lewis]

I'm still going to check for voltage drop at the motor.

Great. I know Gary measured a pretty significant drop when he did the test.

2.0 volts on the positive side and .6 volts on the negative side. Together that's a 20% drop as the battery was at 12.9 volts at the time.

And I disagree with Dave that regular cabs don't need more flow. Big Blue's A/C had to run on High most of the time, and it was supposedly fully charged. Yes, the evaporator was partially clogged, but not badly.

[BullnoseLuvr]

That's a really neat tool! I'm jealous.

Gitcha one.

Mark

[BullnoseLuvr]

I'm confused - why two sets of pics? What changed?

Also, is the air speed in FPM or what?

The anemometer is so sensitive you should take multiple readings and average if you want to do it right. Nothing changed and you can see the difference. It matters where in the vent and at what angle you place the tool.

It’s in Ft/min. There are other scales but I forget what they are. I think you can measure volume or CFM but you have to make a funnel device scaled properly for the size of the outlet you’re measuring.

Mark

[BullnoseLuvr]

2.0 volts on the positive side and .6 volts on the negative side. Together that's a 20% drop as the battery was at 12.9 volts at the time.

And I disagree with Dave that regular cabs don't need more flow. Big Blue's A/C had to run on High most of the time, and it was supposedly fully charged. Yes, the evaporator was partially clogged, but not badly.

Is that hot side from the battery, relay, or elsewhere?

“More” is a relative term. Before I cleaned everything up and swapped the evap I knew I needed more flow. Not anymore — this thing has plenty of flow. So it depends on where Dave (or anyone) is starting from.

Mark

 

[kramttocs]

2.0 volts on the positive side and .6 volts on the negative side. Together that's a 20% drop as the battery was at 12.9 volts at the time.

And I disagree with Dave that regular cabs don't need more flow. Big Blue's A/C had to run on High most of the time, and it was supposedly fully charged. Yes, the evaporator was partially clogged, but not badly.

Is that hot side from the battery, relay, or elsewhere?

“More” is a relative term. Before I cleaned everything up and swapped the evap I knew I needed more flow. Not anymore — this thing has plenty of flow. So it depends on where Dave (or anyone) is starting from.

Mark

We referenced it in another thread recently but check this thread out if you haven't yet. Good discussion about the mod.

http://forum.garysgaragemahal.com/Current-going-to-Blower-Motor-can-be-higher-than-Headlights-why-no-relay-mod-tp566.html

[BullnoseLuvr]

We referenced it in another thread recently but check this thread out if you haven't yet. Good discussion about the mod.

http://forum.garysgaragemahal.com/Current-going-to-Blower-Motor-can-be-higher-than-Headlights-why-no-relay-mod-tp566.html

I already devoured that thread. I can search the forum and find where the hot side test point was. *sigh*

Mark

[kramttocs]

We referenced it in another thread recently but check this thread out if you haven't yet. Good discussion about the mod.

http://forum.garysgaragemahal.com/Current-going-to-Blower-Motor-can-be-higher-than-Headlights-why-no-relay-mod-tp566.html

I already devoured that thread. I can search the forum and find where the hot side test point was. *sigh*

Mark

Apologies if that came across the wrong way. That thread just has the diagrams in it and discussion to go with.

The voltage test (Gary can confirm/deny this is where he measured his drop) should be done at the blower motor connector C603 connecting the positive wire there with the battery ground. That's as close as you can get to the motor as well as the most logical place (both in effectiveness and accessibility) to insert the relay.

Is that what you are asking?