tsmooth

Hi guys,

i screwed up something but im not sure what.
i bought a 2012 f150 5.0 a few months ago. everything has been awesome... just wished the ac blew a little harder. after replacing the air filter on my wifes honda pilot and having a great improvement in airflow after replacing the filter got me thinking maybe the evap is clogged a bit on my f150. my research shows that my truck doesnt have a cabin filter to protect the evaporator.

i found a video on youtube of a guy cutting a hole behind the glovebox and spraying down his evaporator with a garden hose to clean off the evap and get air flow back or increased. i cut my hole where he did, except in his video he said he used full spray... i did not. I put my nozzle on mist setting and would spray a minute and then let the water drain. the water coming out was milky brown so i figured i was making some headway. i finished... plugged the hole i made and turned the truck on... no cold air. drove the truck a few blocks with no change in teperature. leading up to the start of the project the ac blew cold and the thermometer in the ac vent would get to 42.

i let the truck sit overnight before trying anything again, went out started the truck in the morning and no cold air. at one point i was opening and closing the hole i made behind the dash thinking there was still moisture in there that maybe wasnt allowing the ac system to cycle and the air got cold. the temp dropped to 80 on the vent thermometer and then started going back up. i havent been able to repeat this result all day since.

i have tried testing fuses and swapping out the relay for another relay in the box and nothing gets the ac compressor to engage.

i found a video on how to override the ac relay and tested the ac clutch using a paperclip to close the system. the clutch engaged, so i started the car and closed the system with the paperclip while running and the compressor engaged and the ac got cold... i didnt run the truck much longer than a minute like this cause im not 100% sure im not causing further damage i just wanted to eliminate that my compressor hadnt gone bad.

this is where i am stuck. i dont know what i could have ruined. but im sure you guys will let me know.

swapping out the relay with another like relay (there are 4 others used in my fuse box that are the same) didnt solve the problem. which makes me think there is something else wrong.

i appreciate any attention anyone has to give this issue.

Joe F

I don't know what's wrong, but I am going to follow this thread. I have seen the video before that you referenced, or one like it. I've always wondered what the risks were so I hope you get it figured out.

tsmooth

Oh i figured it out... its my own fault, not being as careful as i thought i was while cutting open the hole to gain acess to the evaporator.

while cutting the top of the square i was cutting in a right to left motion and the blade slipped a few times. Unbeknownst to me i had cut through only one of the two tiny wires to the left of the hole in the video that go from the top of the box to the middle and then disapear into the middle of the box for what i think is a thermostat wire. I didnt find it until i was doing some further investigation tracing wires cause i was gonna pull the blower motor out and see if water was puddled up and to get a view of the front of the evap. I was tracing the blower wiring harness to better see how to get it completely out and i happened on what i think is the thermostat wire... if i hadnt traced it with my fingers i would have never noticed one of the two wires was cut. I cut and stripped the wires and spliced in some 14 guage i had on hand (way too big) but my ac is COLD! Now im gonna go get some smaller wire and solder it in for a permanent fix. Im gonna go back in with some evap cleaner and rinse it out one last time now that i know i didnt ruin anything.

Joe F

Well congrats then! What did you use to make the cut? Dremel? I may get brave enough to take this on one day in my 2013. With no cabin filters in these things (which I really don't get), I'm sure that after 5 years my evaporator looks like mac n' cheese in there. Now that you're here though, stick around and set a spell. Lots of good info going around in here.

tsmooth

A utility knife. Dremmel may work. i find that the utility knife doesnt displace too much material and you almost dont need tape when you push it back together.

the vid you posted is the exact video im using as a refference. You can see the two wires coming down from the top of the box and run just to the left of the hole he cut.

yeah... dont cut those.

tsmooth

I would say go ahead and do it. Theres pretty much no risk. I did get some improvement in air flow and reduction in temperature. My temperature on my in vent thermometer was pegged at 40 in 96 outside temp. Havent had it go below 42 since ive owned it.
2 degrees doesnt sound a lot but it makes a big difference in how comfortable you get. And im in vegas so 2 degrees is a huge success.

which makes me wonder... did i realy get more air flow or do i only think that cause its colder.

im going to look into a heater core bypass valve install that shuts off the water going into the heater core from the engine when the ac is on. Even though the hot water doesnt go through the heater core the hot water still goes through the firewall and into the ac box causing a radiant heat from the hoses. Some things i have read have reported a few degree decrease. I would love to have 38 degree air at the vents...

tsmooth

I went ahead and used a cleaner on the evap and rinsed it... no additional decrease in temperature at vents.

Joe F

Thanks for the update. I may give it a go this weekend. I don't seem to have any air flow problems as it can still ruffle my hair when set on high, but being in the extremely humid southeast, I do get some smell on startup on extremely muggy days. Would love to flush out the 5 years of crud that's probably accumulated in there that gives off odor when it gets damp. Did you have any issue pushing the utility knife through the plastic to start the cut? I looked up in there and that plastic seems pretty sturdy. Thanks again!

digitaltrucker

You can:

https://www.f150forum.com/f38/compre...ng-fix-271852/

tsmooth

Thanks for the post. Ive read through most of it. I dont entirely understand the install of that ohm devise... i understand what it does.

ive since gone to home depot and purchased pipe insulatuon. For 1/2 od pipe and fit it arround the cold line (fat line) going from the firewall to the compressor. There was about 8 inches total of insulation from the factory. It was only on a few sections and didnt wrap completely arround the pipe. I insulated everything i could of the fat line.

two things have improved. Today was a 105 degree day. Driving to homedepot ac would get to 45. As long as i was up to speed. Accelerating after turns or stops would see sometimes as high as 55, especially if i was at a stop. After wrapping the fat line (cold to the touch while ac is on) i never saw the surging while accelerating, ac at vents didnt go above 42. Got as low as 39 once i was up to speed. I was only doing a test drive up a long straightaway. Max speed 45mph. So ill report what happens at freeway speed. But as i saw in the research this insulating the cold line made a difference. My next step will either be the heater core bypass valve or ceramic based window tint.