IM 839

Group: PTACPart No: 668103501Date: March 2006

McQuay® Packaged Terminal Air ConditionerHeat Fan Lockout Control for Digital Control SystemKit Part No. 107039301

Installation and Maintenance

©2006 McQuay International

5. Pull Black Jumper clip from HFLO terminals onPCB (Figure 2).

6. Thread HFLO sensor wires through hole in bottomof control box so that the new sensor wireconnector can be connected to the previouslyjumpered HFLO terminals on the PCB (Figure 3).

Safety InformationThe installation of this equipment shall be in accordancewith the regulations of authorities having jurisdiction andall applicable codes. It is the responsibility of theinstaller to determine and follow the applicable codes.This equipment is to be installed only by an experiencedinstallation company which employs trained personnel.

DescriptionThe factory supplied Heat Fan Lockout (HFLO)control is a field mounted aquastat that clips-on to thehot water or steam return piping. When the unit is inHeat Mode, but hot water or steam are not available, itprevents the indoor fan from operating.

Tool Required• 1/4" Nut driver

Installation Procedure1. Disconnect all power from the unit by unplugging

the power cord from the receptacle.2. Remove front cover.3. Slide unit chassis 3"-4" forward to facilitate access

to the control box.4. Remove screws that will allow access to the inside

of the control box and to the Printed Circuit Board(Figure 1).

Figure 1. Remove screws that will allow access to the inside of thecontrol box and to the Printed Circuit Board (PCB)

IM 839 Page 2 of 3 Heat Fan Lock Out Control for Digital Control System ©2006 McQuay International

Rigorously adhere to field wiring procedures regarding properlockout and tagout of components.

To avoid electrical shock, personal injury or death:1. Installer must be qualified, experienced technician.2. Disconnect power supply before installation to prevent electrical

shock and damage to equipment.

WARNING!

WARNING!

Disconnect all electrical power before servicing unit.Electrical shock will cause severe injury or death.

! DANGER

Sharp metal edges are a hazard, use care when servicing toavoid contact with them.

! CAUTION

Jumper Clip

Figure 2.

Figure 3.

©2006 McQuay International (800) 432-1342 www.mcquay.com IM 839 Page 3 of 3

McQuay Training and DevelopmentNow that you have made an investment in modern, efficient McQuay equipment, its care should be a high priority.For training information on all McQuay HVAC products, please visit us at www.mcquay.com and click on training, orcall 540-248-9646 and ask for the Training Department.

WarrantyAll McQuay equipment is sold pursuant to its standard terms and conditions of sale, including LimitedProduct Warranty. Consult your local McQuay Representative for warranty details. Refer to Form933-43285Y. To find your local McQuay Representative, go to www.mcquay.com.

This document contains the most current product information as of this printing. For the most up-to-date product information,please go to www.mcquay.com.

7. Check to be sure no wires are pinched in thecontrol box sections and replace all screwsremoved in step 4.

8. Locate Return piping, clean sensor location withsteel wool or very fine sand paper and affix HFLOsensor to the piping with the sensor clip provided(Figure 4).

Sensor Wire Connector Connects to PreviouslyJumpered HFLO Terminal on PCB

Sensor Wire

9. Slide chassis back into wall sleeve and secure withscrews.

10. Replace front cover.11. Reconnect power cord, start unit, test and check

for proper operation. If there is heat in theHydronic coil and the Unit is in the “Heat” mode,the sensor should allow the indoor fan to operatewhen Heat is called for. If the fan does notoperate, check to be sure that the HFLO sensorwires are in fact connected to the HFLO pins andnot the OA Damper pins.

If there is NO heat in the Hydronic coil, the fan shouldoperate in the “Fan Only” and the “Cool” modes butNOT in the “Heat” mode.

Sensor Clip

HFLO Sensor

Figure 4.

Return Piping