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

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BullnoseLuvr

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

As a step in rebuilding my A/C I pulled the evaporator out today and a considerable amount of vegetable matter poured out of the blower box and the resistors were completely encased in debris. The evaporator didn't look especially dirty but I couldn't see much light through it. I installed the new evaporator and buttoned everything back up and whoa nelly! That thing blows like a... well, it blows really hard. Like amazingly hard.

I don't know if it was the debris, a dirty evaporator, or both but it's a dramatic improvement -- enough that I'm not going to bother doing the relay mod.

If you pull the blower and clean the box and don't get good results it might not be a bad idea to pull the evaporator out and wash hell out of it with a strong nozzle. Fortunately it's possible to pull the evaporator and swing it out without discharging the system.

I'm going to measure airflow at each of the vents with my anemometer (pictured below) and report back.

Mark

‘84 F150 4x4 351W 4sp. Regular cab, long bed, all original. '69 Continental MK III. Older restoration. '95 Saab 900S Convertible. '05 Saab 9-3 ARC Convertible 2.0T. Lime Yellow. '09 Saab 9-3 AERO Convertible 2.8T. Sand Beige top. '13 MINI Cooper Factory JCW 6sp. '01 H-D Sportster. '03 Yamaha FZ-1.

Gary Lewis

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

Administrator

Now, if you'd just go measure Scott's or Jim's air flow with their relay mod's we'd know how much improvement they make. Of course, that's assuming their evap's aren't clogged.

Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

1986F150Six

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

Administrator

Too bad you did not measure the air flow before the work you have done, for a true comparison. Good work!

kramttocs

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

Administrator

In reply to this post by Gary Lewis

In the name of science I just ordered one of these.

I replaced my evap and have only had the fan on for at most 6 hours of highway driving. Otherwise it has been windows down since the un-modded vent setting is hot.

Scott
'Camano' 1986 F250 Supercab XLT Lariat 460/C6
'Chanute' 1980 F350 C&C 400/NP 435 - Gin Pole

But there ain't nothin' wrong with the radio

Gary Lewis

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

Administrator

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

Gary, AKA "Gary fellow": Profile

BullnoseLuvr

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

In reply to this post by 1986F150Six

I would have had I known replacing the evap would make such a change.

Mark

FuzzFace2

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

In a regular cab I don't see the need to have the fan blow more than it does.
I turn the fan on high when I first get in after work because it is hot, 90*+ OAT but once the cab is cooled down I cut the fan speed back.
Dave ----

Dave G.
81 F100 flare side 300 six / AA OD / NP435 / 2.75 gear
http://cars.grantskingdom1.com/index.php/1980-Ford-F100?page=1
81 F100 style side 300 six/SROD parts truck -RIP
http://cars.grantskingdom1.com/index.php/1981-Ford-F100

BullnoseLuvr

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

In reply to this post by kramttocs

kramttocs wrote

In the name of science I just ordered one of these.

I replaced my evap and have only had the fan on for at most 6 hours of highway driving. Otherwise it has been windows down since the un-modded vent setting is hot.

Welcome to the rabbit hole...

Mark

kramttocs

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

Administrator

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.

Scott
'Camano' 1986 F250 Supercab XLT Lariat 460/C6
'Chanute' 1980 F350 C&C 400/NP 435 - Gin Pole

But there ain't nothin' wrong with the radio

BullnoseLuvr

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

In reply to this post by BullnoseLuvr

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

BullnoseLuvr

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

In reply to this post by kramttocs

kramttocs wrote

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

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

Administrator

In reply to this post by BullnoseLuvr

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

Also, is the air speed in FPM or what?

Gary, AKA "Gary fellow": Profile

kramttocs

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

Administrator

In reply to this post by BullnoseLuvr

BullnoseLuvr wrote

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.

Scott
'Camano' 1986 F250 Supercab XLT Lariat 460/C6
'Chanute' 1980 F350 C&C 400/NP 435 - Gin Pole

But there ain't nothin' wrong with the radio

Gary Lewis

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

Administrator

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.

Gary, AKA "Gary fellow": Profile

BullnoseLuvr

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

In reply to this post by Gary Lewis

Gary Lewis wrote

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

Gitcha one.

Mark

BullnoseLuvr

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

In reply to this post by Gary Lewis

Gary Lewis wrote

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

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

In reply to this post by Gary Lewis

Gary Lewis wrote

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

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

Administrator

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

Scott
'Camano' 1986 F250 Supercab XLT Lariat 460/C6
'Chanute' 1980 F350 C&C 400/NP 435 - Gin Pole

But there ain't nothin' wrong with the radio

BullnoseLuvr

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

kramttocs wrote

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

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

Administrator

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?

Scott
'Camano' 1986 F250 Supercab XLT Lariat 460/C6
'Chanute' 1980 F350 C&C 400/NP 435 - Gin Pole

But there ain't nothin' wrong with the radio