MonteCarloSS.com
MonteCarloSS.com
Previous Thread
Next Thread
Print Thread
#1058160 - 07/08/18 10:11 AM NEED HELP ON HVAC SWAP  
Joined: Jun 2012
Posts: 138
axld Offline
Member
axld  Offline
Member

Joined: Jun 2012
Posts: 138
lakeland,fl
ok, i have replaced evaporator / condenser/dryer . I have a LSX with a Sanden compressor. I know the low pressure switch is on the Dryer. I have no high pressure switch , was it on the original compressor (I cant remember been so long ago since i had one)? do i need a high switch? where to put it? BTW , I am going to have to have custom lines made as I swapped out to a IROC condenser ( both lines on pass side where my compressor is).


86 SS . Custom Paint. Built 6.0 with LS3 Top End .TSP Custom grind cam.TKO 600 5 spd. Quick 9'' / 3.70 Gearing. ZQ8 Spindles. KORE3 12.8'' frt Brake Kit. UMI Rear Adjustable UCA. Rear LCA. UMI Front Chassis Bar. BMR Coil Springs. BMR Rear Sway Bar. N90 17'' Wheels . 255/45-17 Nitto 555 G2's. SO FAR..............lol.
#1058161 - 07/08/18 02:07 PM Re: NEED HELP ON HVAC SWAP [Re: axld]  
Joined: Mar 2000
Posts: 5,321
upflying Offline
15+ Year
upflying  Offline
15+ Year
Member

Joined: Mar 2000
Posts: 5,321
Reno, NV
The only pressure switch in my system is the one on the dryer.


86 MCSS Notchback coupe, LS3, 4L65E, QP 9", Eaton Truetrac, 4 wheel disc, column shift, Dakota Digital, silver with maroon bench interior

[Linked Image]
#1058165 - 07/08/18 04:35 PM Re: NEED HELP ON HVAC SWAP [Re: axld]  
Joined: Jan 2000
Posts: 4,064
mmc427ss Offline
15+ Year
mmc427ss  Offline
15+ Year
Member

Joined: Jan 2000
Posts: 4,064
Pottstown, Pa
Are you using the PCM to control the fans?

Using a stand alone controller for the fan I installed a high pressure switch in the high pressure test port. It's purpose is to turn off the fans when the system pressures are low. Such as on a cold day when you need defrost and don't need the fan running to cool the rad and A/C system pressures are low, or running down the highway at 70 mph when the fans would normally be off and you have very good air flow across the condenser and rad, A/C system pressures are also low.

The high pressure switch used would need to be appropriate for the type of freon used, the system high/low pressures vary with different freons. I'm running R12, switch is a 125-190 in my system. A 134 system would need high limits.
Bob

#1058172 - 07/09/18 01:57 PM Re: NEED HELP ON HVAC SWAP [Re: axld]  
Joined: Apr 2011
Posts: 903
Hunter79764 Offline
Member
Hunter79764  Offline
Member

Joined: Apr 2011
Posts: 903
Grand Prairie, Tx
High pressure switch is nice but not required. Low pressure switch is required.
On the high side, your compressor likely has a Pressure Relief Valve that will vent refrigerant if pressure goes too high. If you want, you can put a pressure switch that will cut the compressor clutch before you get to that point. You can also control fans like Bob is doing. Factory systems now use a high pressure SENSOR to tell the ECM to kick on fans or not (along with vehicle speed etc).


Sometimes you just need a bigger hammer...

'85 MC with budget 5.3L swap, TH350 with stock 2.14 rear end
It ain't much off the line, but it's nice on the highway
#1058175 - 07/09/18 04:19 PM Re: NEED HELP ON HVAC SWAP [Re: axld]  
Joined: Jun 2012
Posts: 138
axld Offline
Member
axld  Offline
Member

Joined: Jun 2012
Posts: 138
lakeland,fl
Thanks guys, originally I had the 411 PCM controlling the fans. with the 2nd fan also wired into the AC on switch. With the new engine /trans swap I am installing a FITECH LS SYSTEM. which does the same controlling I believe. ( I am starting on installing that today) . Then on to the HVAC. Have any of you heard of using a Binary switch ( I take it does both?)

Last edited by axld; 07/09/18 04:27 PM.

86 SS . Custom Paint. Built 6.0 with LS3 Top End .TSP Custom grind cam.TKO 600 5 spd. Quick 9'' / 3.70 Gearing. ZQ8 Spindles. KORE3 12.8'' frt Brake Kit. UMI Rear Adjustable UCA. Rear LCA. UMI Front Chassis Bar. BMR Coil Springs. BMR Rear Sway Bar. N90 17'' Wheels . 255/45-17 Nitto 555 G2's. SO FAR..............lol.
#1058176 - 07/09/18 04:58 PM Re: NEED HELP ON HVAC SWAP [Re: axld]  
Joined: Jan 2000
Posts: 4,064
mmc427ss Offline
15+ Year
mmc427ss  Offline
15+ Year
Member

Joined: Jan 2000
Posts: 4,064
Pottstown, Pa
The binary switch has two terminals, can be selected to be used as a high pressure cutout for the system if pressures get to high. It can also be used as in my install for turning the fans on and off dependent on pressure. A trinary switch has three terminals, can control fans and also shut down A/C if pressures get to high.
Here['s a very helpful PDF from 4Seasons, pages 1070-1090 lists all the A/C switches.
I run a 36663 fan switch in the stock high pressure port, R12 used. 134 pressures are higher
http://www.smpbuyersguide.com/4seasons/app.php?RelId=6.11.10.0.9

That's my take on this.
Bob

#1058187 - 07/10/18 08:32 AM Re: NEED HELP ON HVAC SWAP [Re: axld]  
Joined: Jun 2012
Posts: 138
axld Offline
Member
axld  Offline
Member

Joined: Jun 2012
Posts: 138
lakeland,fl
Thanks Bob . I will look into it.


86 SS . Custom Paint. Built 6.0 with LS3 Top End .TSP Custom grind cam.TKO 600 5 spd. Quick 9'' / 3.70 Gearing. ZQ8 Spindles. KORE3 12.8'' frt Brake Kit. UMI Rear Adjustable UCA. Rear LCA. UMI Front Chassis Bar. BMR Coil Springs. BMR Rear Sway Bar. N90 17'' Wheels . 255/45-17 Nitto 555 G2's. SO FAR..............lol.

Random Images
581/thumbs/IMG_5912.jpg
by MonteCarSlow
500/thumbs/IMAG0011-2-1-1.jpg
by Rodney
500/thumbs/Copy_of_011708330hp350.jpg
by Rich.S85SS
500/thumbs/HPNX0071.JPG
by Intmdatr3
500/thumbs/montedecaled_008.JPG
by Monster
Help MonteCarloSS.com


Recent Contributors
Rob Forbes
techjay
Authorized Vendors
Tell them you saw it
on MonteCarloSS.com!


CustomMonteSSParts.com
Dixie Monte Carlo Depot
GSI Interiors
HRpartsNstuff
Mikes Montes
Savitske Classic & Custom
Powered by UBB.threads™ PHP Forum Software 7.6.0